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A few varieties immune to smut are at the same time immune to crown

rust and mildew.

The same is observed in other plants. So in vines, American varieties

are simultaneously immune to

Plasmopara vilicola, Uncinula necator,

Manginia ampelina.

European varieties are susceptible to all these diseases.

In roses varieties strongly immune to mildew are resistant to rust too.

As to exceptions to these regularities, they are but very few and parti

cularly in heterocious rusts (e. g. in

Cronartium asclepiadeum, Puccinia

isiaceae)

and in one stage of development only. These examples ought

to be more fully studied.

— 23Г. —

CHAPTER 5.

Immunity as a Physiological Test in Genetics and Systematic».

This chapter is a continuation of the 4-th Chapter and represents a

considerably enlarged exposition of view's and facts on the application of

reactions of varieties and species in relation to narrowly specialised para

sites as a physiological test in Genetics and Systematics, published by the

author in 19141). The author gives many new examples of the application

of fungous tests for genetical and systematical studies, which w'ere simul

taneously proved by the aid of other methods used for establisheing

phylogenetical relations of organisms: hybridisation,serum reactions,cytology.

So in oats,the species

Лvena diffusa

As. & gr.

,A nuda L.var. inermis

Kcke.,

A. orientalis Schreh., A. /aluaL., A . Ludoviciana

Dur. in general are characte

rised by susceptibility to smut, rust, and mildew; species

A. hcvis

Roth.,

slrigosa

Schreb.,

A. nuda

1>.

var. biaristata

As. et Gr. in general, on the cont

rary, are immune to all these parasites. A ll 5 species of the first group could be

crossed with one another; the 3 species of the second group easily cross

with one another, as was proved by the author. But the species of the first

group could not be crossed with

t.ho

species of the second group. Cytologically,

as was shown by Miss A. G. N i с о 1 a о v (Moscow), the first group

is characterised by a great number (40—Д4) of chromosomes (diploid); the

second group of species by a small number of chromosomes (14— 16).

For wheat and oats there is given a new scheme of phylogenesis on the

basis of these investigations.

This method can sometimes be very useful to genetists as well as to

systematists,even for practical purposes of plant-breeding, especially in

giving useful suggestions, as to the possibility of crossing some species

and varieties which morphologically may be quite distinct. For phyloge

netical purposes this method can be used in the same way as hybridisation,

serum reactions, cytology, etc.

l) N. 1. V ;* v i 1о v. Immunity to fungous diseases as a physiological test

in Genetics and Systematics, exemplified in cereals. Journal of Genetics. Yo!. 4. Л? 1

1914 (in English).

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