

LOTSY, CURRENT THEORIES OF EVOLUTION. 409 
of any particular isolation may be extremely complex. As, more- 
Over, the sporangiospores are delimited and the walls of the 
zygogametes laid down without any apparent regard either to the 
conditon, the number, or the position of the nuclei they separate, 
there is no absolute surety that two single-spore strains derived 
from an original single-spore strain will have the same genotype.” 
_ After discussing some other cases he continues: 
„These considerations applied to the fungus Botrytis cinerea 
throw an entirely new light upon the value to be attached to the 
colourless strain. Botrytis cinerea possesses a multicellular mycelium, 
each cell of which contains many nuclei. The conidiophores are 
multinucleate and a small but indefinite number of nuclei pass into 
each conidium. Throughout the whole of the vegetative and reproduc- 
tive mycelium the septa are laid down by a diaphragm-like growth from 
. the hyphal walls, irrespective of the number or condition of the 
nuclei thus separated. Each conidium therefore merely reproduces 
the genetic constitution of the original cell of the mycelium in 
which its conidiophore arose. Many thousands of such asexual 
generations, would therefore, not alter the genetic constitution of 
the organism, and there is no sexual process. The possibility of 
genetic contamination is brought about by the occurrence of hyphal 
anastomoses. In the extremely rare chance of a fertile conidiophore 
arising from a cell contaminated by the nuclei or cytoplasm of a 
genotypically different individual lies, I believe, the explanation 
of the colorless form of Botrytis described. While this possibility 
exists, it is more consonant with the principles of scientific metho- 
dology to accept this interpretation than to formulate a mutational 
hypothesis of the origin of the aberrant strain.” 
In the case of bacteria, we know so little of the cytology that a 
proper discussion is not possible, but it is rather a suggestive fact 
that from different sides sexual reproduction is now claimed to 
occur among bacteria and that acase is known in which the altered 
form constantly gives rise to two types of colonies, one similar 
to the obvious parent and one like itself, the former breeding true, 
the other later again splitting off the former, a behaviour like that 
of a hybrid, splitting off recessives. 
As to Protozoa we know so little as yet about the significance 
of their mikro- and makronuclei in heredity that no conclusions 
