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174 BOTANICAL GAZETTE [SEPTEMBER 
of sperm cells (it is not clear whether he means body cells or male 
cells) in Cupressus goweniana. 
It thus seems to be an established fact that more than two pro- 
thallial cells and more than two sperms occur in widely unrelated 
gymnosperms. Though we may all be willing, perhaps, to accept 
this statement of facts, there is no such unanimity of opinion as to 
the interpretation of them. It is obvious that one may adopt either 
of two views: (1) One or two prothallial cells were found in the 
primitive gymnosperms and in some cases these have divided to form 
a complex. This would be Jerrrey’s (5) “‘coenogenetic prolifera- 
tion.” In support of this view he has urged that a multiplication of 
prothallial cells is correlated with “protosiphonogamic” fertilization 
in the Araucarineae, “since the length of the pollen tube, in the 
absence of any special conductive tissue, such as is found in angio- 
sperms, calls for a greater development of prothallial tissue.” This 
line of reasoning could hardly be extended to Podocarpus or to 
any other case now known. If one could find some physical cause 
applicable to all cases, he might believe that this multiplication of 
cells is a thing of recent origin in each case. Furthermore, the idea 
that a multiplication of cells would be forthcoming just when needed 
is more teleological than accords with modern physiological teaching. 
If we do not accept this explanation, as I think we cannot, we May 
turn to the other possibility. (2) Primitive gymnosperms had 4 
multicellular prothallial tissue, and not unlikely a spermatogenous 
complex of several cells. The evidence for this view is of two sorts, 
historical and theoretical. Historically we know that the pollen 
grains of certain Cordaitales (10) and Cycadofilicales (9, 10) 11) h 
a considerable tissue of some sort. Whether it was spermatogenous 
or prothallial is not very material, since this view assumes that bot 
sorts existed somewhere in the ancestry of living gymnosperms 4? 
that by a gradual reduction each sort has been reduced to one 
two cells. It is of interest to note that all the heterosporous pterido- 
phytes show the same tendency, each of the living genera having 4 
single prothallial cell and in some cases producing as few as 10UP 
sperms. ‘This assumption makes it easy to account for the facts 
already related. We have but to suppose that in these cases si 
forms showing these peculiarities have merely retained their primipve 
ie 
