ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 767 



Desmothoraca. With regard to the multinticlear condition of various 

 forms, we find just the same conditions as among the Rhizopoda ; 

 a large number have, so far as yet known, only one nucleus ; others, 

 such as Vampyrella sp., have three, Nuclearia delicatula has five or 

 six, and Actinosjyhcerium possesses 100 to 200 nuclei, and (according 

 to the observations of Carter) may have 300 to 400. In these forms 

 the nucleus has a definite position within the endosarc. There may 

 be a number of nucleoli in the nucleus. The characters of the 

 pseudopodia of ActinospJiCErium are especially insisted on, and it is 

 pointed out that, just as in the fine pseudojjodia of the Ehizopoda, 

 streaming movements are to be seen in these processes. The phe- 

 nomena of reproduction are carefully described, and the difficulties as 

 to the explanation of the process of conjugation examined. 



BOTANY. 



A. GENERAL, including Embryology and Histology 

 of the Phanerogamia. 



Development of the Embryo of Grasses.* — C. Nomer has closely 

 investigated this subject, esjDecially in the cases of the common 

 cereals, barley, wheat, rye, and oats. The fertiKzed ovum (oosphere) 

 is in all cases first divided into three segments by two cell-walls 

 formed rapidly one after the other. But according to the position of 

 these segment-walls, three diflerent types of development may be dis- 

 tinguished. In the first type, the two segment-walls are parallel, 

 and are found in basipetal succession ; and a three-celled embryo is 

 thus the starting-poiut for fui'ther cell-divisions. In the second type 

 the second segment-wall is not parallel to the first, but meets it at 

 an acute angle ; while in the third the first wall is oblique to the 

 longitudinal axis of the embryo, the second again meeting the first at 

 an acute angle, the size of which varies greatly. These two last 

 types of development had hitherto been almost overlooked ; but all 

 three occur in the development of the embryo even of the same 

 species. The fiu-ther course of development is traced by the author in 

 detail in a number of instances. 



The best mode of treatment of the embryo of grasses was found by 

 the author to be as follows : — The ovary was laid for a considerable 

 time in absolute alcohol. Shortly before being examined it was taken 

 out and placed in a mixture of alcohol and distilled water, to prevent 

 its becoming too hard for section. It was then taken between 

 the finger and thumb, and sections carefully made with the razor in 

 the longitudinal direction ; these were laid on the slide, and a drop 

 of very dilute potash added. The embryo-sac or the section which 

 contained the embryo was next taken out, and placed in a small 

 quantity of distilled water on a fresh slide. The embryo was then 

 carefully removed from the endosperm with a needle under the 



* Flora, Ixiv. (ISSl) pp. 241-51, 257-66, 273-S4 (4 pis.). 



3 E 2 



