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Proceedings of the Royal Society 
of being rationalised. Thus, if the ovinn he a predominantly 
anabolic cell, in an environment tending towards the increase of 
anabolism, the occurrence in so many groups of degenerate ova which 
are wholly nutritive becomes intelligible. They have passed the limit 
of normal anabolism, and have become too anabolic to divide. So 
the various kinds of spermatozoa, from the ordinary ciliated type to 
the sluggish amoeboid form of many Arthropods, may be arranged 
according to the degree in which katabolism diminishes. The amoe- 
boid forms partly equipped with nutriment persist, as is well known, 
for a prolonged period, which would be quite impossible for the 
rapidly moribund ordinary types. Experimental researches like 
those of Zacharias and others on the action of reagents, &c., on 
sperms, such facts as the artificial reversion to the amoeboid type, 
the attraction of sperms most powerfully to the most nutritive solu- 
tions, and so on, acquire a new meaning and importance. 
(2) So, too, in the phenomena of maturation, the formation of 
polar vesicles seems rightly interpreted as an extrusion of the katabolic 
or male elements from the preponderatingly anabolic ovum. The 
close parallelism between spermatogenesis and oogenesis, which has 
been elsewhere insisted upon,* holds good here also. The extrusion 
of protoplasmic elements at various stages in spermatogenesis, but 
especially in the sperm mother-cell or sper- 
y matogonium, which is homologous with 
the ovum, may be similarly expressed 
as a separation of predominantly ana- 
bolic material. In this connection it is 
worth noting ho wYanBeneden and Julin 
have, in their researches on oogenesis and 
Spermatogenesis. spermatogenesis in Ascans , emphasised 
the exact morphological correspondence 
of the two processes. A further corroboration of a different char- 
acter has been afforded in the microchemical demonstration of the 
similar staining reactions of polar vesicles in ova, and the blasto- 
phore remnant in spermatogenesis. Further, in the differentiation 
of the reproductive elements in most plants, certain elements are 
observed to be separated off, and these admit of being similarly 
* “History and Theory of Spermatogenesis,” Geddes and J. Arthur 
Thomson, Proc. Boy. Soc. Edin ., 1886. 
