716 TRANSACTIONS OF SECTION K. 
logical Society in 1911, but without illustrations. The present paper was accom- 
panied with a full set of illustrations, which the author hopes to publish in 
1914 in an additional volume of his ‘Researches on Fungi.’ 
6. The Structure, Life-history, and Systematic Position of the Genus 
Microspora. By Professor G. 8. Wrst, M.A., D.Sc. 
Although various species of Microspora are amongst the commonest of Green 
Alge, their structure and life-histories have been very imperfectly known, a 
state of affairs which has resulted in much controversy regarding the systematic 
position of the genus. The published accounts of the cytology of the genus 
are in general very defective. In M/. twmidula and one or two others the cell- 
wall becomes disarticulated into H-pieces on the liberation of the zoogonidia or 
on the death and decay of the filament. In M, stagnorum and others the cell- 
wall never breaks in this manner. The chloroplast is a reticulum of variable 
character, but with the exception of M. stagnorum is fairly constant for each 
species. Pyrenoids do not occur. 
The zoogonidia were biciliated in all the cases observed, and arose singly 
from the vegetative cells. In M. twmidula they are liberated by the dissociation 
of the entire filament into H-pieces, but in M. stagnorum their liberation is 
brought about by the rapid conversion into mucilage of the lateral walls. 
Various conditions intermediate between these two types of zoospore-liberation 
are found in other species. 
Aplanospores and akinetes are formed in most species, the akinetes of 
M. floccosa being the most frequently met with. If kept in water these 
akinetes were found to undergo no change for a period of two years, but if dried 
for a few weeks and then placed in water they very soon germinated, growing 
directly into a new Microspora-filament. 
No gametes were observed in any of the species. 
A careful consideration of the characters of the various species indicates that 
Microspora is best placed in a separate family, the Microsporacee, of the 
Ulotrichales. 
7. Zygnema ericetorum and its Position in the Zygnemacee. 
By Professor G. 8. West, M.A., D.Sc., and Miss C. B. Starkey, M.Sc. 
A careful cytological examination of specimens of this Alga from various 
localities reveals the fact that the chromatophores have been incorrectly 
described. There is only one chloroplast in each cell, remarkable for its com- 
paratively entire margin. It is deeply constricted in the middle, and the 
nucleus reposes in the constriction. One conspicuous pyrenoid is present in 
each half of the chloroplast, which may sometimes be twisted through 180° at 
the point of constriction, Cells with two chloroplasts are unusual and generally 
abnormal. 
A cytological examination of Zygnema pachydermum, described in 1894 from 
the West Indies, shows that vegetatively this Alga is identical with Z. erice- 
torum, and moreover its conjugation is quite normal as in other species of 
Zygnema. Hence, it appears highly probable that the genus Zygogonium as 
upheld by De Bary (1858), Wille (1909), and others, is based upon an error, 
since the conjugated specimens of ‘Zygogonium didymum’ (= Zygnema erice- 
torum) figured by De Bary are very likely monstrous forms. 
8. Evidence which shows that Mutation and Mendelian Splitting are 
Different Processes. By Dr. R. Ruaates Gates. 
Definite evidence has been obtained showing that some at least of the muta- 
tions of CEnothera are not due to recombinations of Mendelian characters, as 
various writers have assumed, but to irregularities in meiosis, which lead to 
changes in nuclear structure. The cases of @. lata and @. semilata only will 
be referred to in this paper, because they offer a means of differentiating be- 
tween characters which are inherited from the parents and those which arise as 
