and Laboratory Methods. 1575 



produced, but fail to germinate as filaments, growing directly into the round 

 celled form. By varying the porportions of the four salts contained in the 

 nutrient fluid and yet keeping its osmotic pressure the same, an attempt was made 

 to determine whether these changes in the form of the alga were due to a physi- 

 cal or chemical cause. Many cultures were made in this way with a uniform 

 result ; the form of the plant is always determined by the osmotic pressure of 

 the surrounding medium and is never influenced by the varying proportions of 

 the constituent compounds. Some considerations follow concerning the probable 

 way in which variations in the osmotic pressure of the medium may affect the 

 organism. The author believes that the effect is produced by a change in the 

 water content in the cell. Whether or not the rounding up of the cells in the 

 strong solution has any connection with the process of plasmolysis is a question 

 which he discusses at some length. The results of the different experiments are 

 shown by full tables and by two excellent plates of half-tone reproductions of 

 photomicrographs. This work opens up an entirely new field in plant physiology, 

 and it is to be hoped that further research on the influence of osmotic pressure 

 in nutrient media may be forthcoming. J. B. Overton. 



Chicago. 



Guignard, L. La double ficondation dans le The details of fertilization in Naias 

 Naias Major. Jour de Bot. 15: i-g, igoi. , ^ ,.„ ^. ,, , 



^ ^ major do not diner essentially from 



those in other forms. The chromosomes are very long and the gametophyte 



number is six, being the smallest number yet observed in any plant. The male 



nuclei are elongated, but do not assume the vermiform appearance so conspicuous 



in those of the Compositae. One synergid disintegrates soon after the entrance 



of the pollen tube, the other, in general, remains intact until after several 



divisions of the embryo. The fertilized egg does not rest for a time, as is usual 



in other forms, but divides immediately after fusion is effected. One figure 



shows the fertilized endosperm nucleus in the spirem stage, and the embryo two 



celled. In all previously described cases of double fertilization, the endosperm 



nucleus invariably divides first. Many times two embryos were observed lying 



side by side, the unfertilized endosperm nucleus lying between them. One of 



the synergids had evidently functioned as an egg, and endosperm was not 



produced. Two of the antipodals soon show signs of disintegration. The upper 



one continues to enlarge long after fertilization. The article is illustrated with 



fourteen text figures. W. J. G. Land. 



Chicago. 



Lyon, H. L. Observations on the Embryogeny Nelumbo is certainly a perplexing form. 

 ofNelumbo. Minnesota Bot. Studies, 2: -j^he closed bundles, irregularly 

 643-655, 1901. ° ■' 



scattered, present a distinctly mono- 



cotyl feature ; the leaves with reticulate venation suggest dicotyls, while the 

 flowers might be either monocotyl or dicotyl. The earlier observers, dealing 

 with mature seeds, have described the embryos of Nelumbo and of other mem- 

 bers of the Nymphaeaceae as monocotyl. Material for the present work was 

 collected in August, 1899, and August, 1900, in southeastern Minnesota, where 

 acres of Nelumbo lutea grow in the bayous of the Mississippi river. A study of 



