ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 655 



B. CRYPTOGAMIA. 



Apospory in the Thallophyta.* — Prof. W. E. M'Nab calls atten- 

 tion to certain phenomena in the Peronosporeaa and in Vaucheria 

 which are to be regarded as cases of apospory, which occurs only 

 under certain conditions. In Cystopus candidus the moniliforra 

 series of cells found below the epithelium of the host and usually 

 called conidia, are to be considered rather as detachable sporangia, 

 from comparison with other members of the group. In 0. Portulacese 

 the first and oldest sporangium of the series behaves differently from 

 the remaining ones ; it does not liberate its contents, but developes 

 directly into a new thallus ; it is aposporous. 



Phyfophthora infestans exhibits apospory when the sporangia are 

 grown in moist air, hypha? being produced ; whereas if placed in 

 water zoospores are developed. 



Peronospora gangliiformis and P. parasitica also exhibit the 

 phenomena. 



In Vaucheria tuberosa there is a complete series of gradations 

 from the production of ciliated zoospores to spores which do not 

 leave the sporangium, and to complete apospory. 



The author does not agree with Bower in regarding as apospory 

 the artificial production of protonema from cut pieces of sporangium 

 in certain mosses ; it rather approaches " histogenesis." 



In Batrachospermum an apospory is apparently present, where the 

 spores are suppressed, the ovum giving rise to a protonema. 



In the Saprolegnieaa apogamy has been observed, and Prof. M'Nab 

 suggests that this is a case of " apandry," where the antheridium 

 fuses with the oogonium. The same term would be applied to the 

 pollen-tube. 



Cryptogamia Vascularia. 



Development of the Antheridium of Ferns.f— Mr. D. H. Campbell 

 describes the development of the antheridium in Onoclea Struthiopteris 

 and sensibilis. 



When the mother-cell of the antheridium is first cut off from the 

 male prothallium, it contains a distinct central nucleus. The first 

 wall formed within the antheridium is funnel-shaped, with the broad 

 portion directed upward. The second wall is approximately hemi- 

 spherical and parallel to the outer wall of the antheridium. Finally, 

 a third wall is formed, resembling the first in form, and cutting off 

 the covering-cell of the antheridium. The antheridium now consists 

 of four cells, three parietal and one central ; the two lower parietal 

 cells are annular, the upper one flat ; each contains a nucleus. The 

 division of the central cell begins either before or immediately after 

 the formation of the covering- cell. The first wall is nearly vertical, 

 and is soon followed by a second vertical one at right angles. The 



* Scientif. Proc. R. Dublin. Soc, iv. (1885) pp. 466-9. 



t Bull. Torrey Bot. Club, xiii. (18S6) pp. 49-52 (1 pi.). Of. this Journal v 

 (1886) p. 493 ; ante, p. 106. 



