1576 Journal of Applied Microscopy 



the development of the embryo shows that it retains a spherical shape until it 

 consists of several hundred cells. The single cotyledon then appears as a 

 crescent shaped organ partly surrounding the plumule. The single cotyledon 

 now becomes bilobed by a localization of growth. The first foliage leaf arises 

 on the side opposite the cotyledon. The radicle is transitory and does not 

 develop into a primary root, but the work is done by secondary roots arising 

 from the hypocotyl. The only character which has kept the Nymphseaceae among 

 the Dicotyls is the apparently dicotyl embryo. Since a study of the development 

 shows that the embryo is truely monocotyl and since the anatomy conforms more 

 closely to the Monocotyls, the Nymphaeacece should be classified as a sub-series 

 coordinate with the Potamogetonace?e, Alismaceae, and Butomaceae in the series 

 Helobiae. 



A future paper will deal with the development of the embryo-sac and fer- 

 tilization, c. J. c. 



CYTOLOGY, EMBRYOLOGY, 



AND 



MICROSCOPICAL METHODS. 



Agnes M. Claypole, Cornell University. 



Separates of papers and books on animal biology should be sent for review to 



Agnes M. Claypole, 125 N. Marengo avenue, 



Pasadena, Cal. 



CURRENT LITERATURE. 



Boveri.Th. Die Polaritat von Ovocyte, Ei und ^^^^^-^ ^33 j^^je the interesting dis- 

 Larve des btrongylocentrotus hvidus. Zoolo- ° 



gische Jahrbiicher, Abth. f. Anat., July, covery that the principal axis of the 



'9°'- Strongyloicntrotns is marked out in the 



egg before fertilization, and that it probably corresponds to the axis of the 

 ovocyte of the germinal epithelium. The unripe egg is surrounded by a gela- 

 tinous envelope which is so transparent that it is invisible under ordinary circum- 

 stances. At one point this envelope is perforated by a micropyle. Into this 

 micropyle the polar bodies are usually extruded. After the maturation divisions, 

 the pigment which previously was scattered uniformly over the (t^g collects into 

 a broad band, surrounding the side of the egg opposite the micropyle. The 

 principal axis of the egg is thus determined. The female pronucleus is eccentric, 

 but stands in no constant relation to this chief axis. Fertilization is usually 

 effected through the micropyle, and the first cleavage spindle lies at right angles 

 to the entrance path of the spermatozoon. This was observed when the sperm 

 entered near the equator of the Qgg, so the first cleavage plane is apparently 

 determined by the entrance path of the sperm. No trace of a bilateral organiza- 

 tion of the egg could be detected, and as the first cleavage plane is not known to 

 stand in any relation to the bilateral symmetry of the larva, the entrance path of 

 the sperm is not known to mark out the plane of bilaterality, as it has been said 

 to do in the frog. The unpigmented animal pole of the egg forms the ectoderm, 

 the pigmented belt, which lies in the vegetal half of the egg, forms the entoderm, 



