620 SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the infundibular membrane of tbe testis ; in this form, again, he 

 was able to detect a nucleus in the pseudonavicella. 



In the intestine of Liihohius forficatus the author observed an 

 oviform psorosperm or coccidium, which, so far as he knows, has 

 never yet been seen in an Arthropod. Here, in addition to the 

 granular protoplasm, there was a pretty large nucleus and a large 

 nucleolus. These appear to give rise to sickle-shaped corpuscles. 

 The author concludes by observing that although their life-history is 

 yet so incompletely known, it is of interest to know that in a Myriapod 

 there are to be found coccidia which have so close a resemblance to 

 the psorosperms observed by Eimer in the mouse. 



BOTANY. 



A. GENERAL, including Embryology and Histology of the 

 Phanerogamia. 



Development of the Embryo-sac* — In pursuance of the observa- 

 tions of Strasburger, Ward, Vesque, and others.f MM. Treub and 

 Mellink have investigated the mode of development of the embryo- 

 sac in some angiosperms. 



A cell of the nucellus, of sub-epidermal origin, produces a longi- 

 tudinal row of from two to five cells. The lowest cell of this row 

 increases in size and becomes the embryo-sac ; the others retreat 

 towards the epidermis of the nucellus, and eventually disappear 

 altogether. The author considers as untenable the view of Warming 

 and Vesque, that the embryo-sac results from the fusion of two or 

 more cells. A careful examination of the history of development in 

 the case of Senecio vulgaris, on the other hand, completely confirmed 

 the description of Strasburger, and the same results were obtained 

 from Luffa petola, Centradenia grandiflora, Anthurium sp., Convallaria 

 majalis, Polygonatum vulgare, Hyacinthus orientalis, and Haworthia 

 suhfasciata. 



In Narcissus Tazelta the mother-cell of the embryo-sac produces 

 normally only two daughter-cells, the upper one of which disappears ; 

 beyond which there is nothing special in the development. In some 

 anomalous cases, however, the upper cell, instead of disappearing, 

 attains a large size, and contains several nuclei; but there is no 

 difference in the lower cell developing into the embryo-sac. 



In AgrapMs pattda the mother-cell also produces only two daughter- 

 cells ; but in this case it is normally the upper one which becomes the 

 embryo-sac. At an early stage the two have the same size, each 

 having two nuclei. The upper cell gradually increases, one of the 

 nuclei placing itself at each end, a large vacuole occupying the 

 centre. The nuclei then divide twice, so that there are four above 



* Arch. Ne'eil. Sci. exact, et nat., xv. (1880) pp. 452-6 (2 pis.), 

 t See this Journal, ii. (1879) pp. 903, 905, 907; iii. (18S0) pp. 107, 472, 473, 

 819 ; ante, pp. 2G0, 264, 266. 



