276 Journal of Applied Microscopy. 



Caldwell, 0. W. On the life history of Lemna The sporophyte of the Leninas, so 

 minor. Bot. Gaz. 27: 37-66, figs. 1-57, 1899. abundant in ponds and sluggish 

 streams, has been frequently investigated, its greatly reduced character making 

 it of special interest. The plants are seldom found in flower and the gameto- 

 phytes have never been studied in detail. In August, 1897, Dr. Caldwell found 

 an abundance of Lemna minor in flower. As far as the structure of the sporo- 

 phyte is concerned, the writer's observations agree in general with those of 

 previous investigators, but he draws the conclusion that " the sporphyte of Le7nna 

 minor cannot be definitely homologized with either a stem or a leaf, but is a 

 shoot undifferentiated except at the basal and nodal regions." The development 

 of the microsporangia and macrosporangia, and particularly the gametophytes, 

 is traced in detail. In each stamen there appears a single archesporial mass, 

 which becomes divided into four masses, or the four loculi of the anther, recall- 

 ing the condition of affairs in Isoetes. The four loculi would then constitute one 

 sporangium and not four. If this interpretation is correct, it will doubtless 

 apply to many other plants. The cells of the tapetum frequently divide and 

 push into the loculus. Many microspore mother cells disintegrate and function 

 as tapetal cells. The generative cell divides into the two male cells before the 

 pollen grain is shed. 



In the macrospore series the archesporial cell gives rise to a tapetal cell and 

 a sporogenous cell, the latter developing directly into the megaspore. It is 

 interesting to note that embryo-sac structures rarely reach a complete normal 

 development, disorganization usually checking the process at some stage. It 

 follows naturally that embryos are extremely infrequent. The numerous excel- 

 lent illustrations are scattered through the text instead of being grouped into 

 plates in the usual manner. In some respects this is very convenient, but it 

 deprives one of the birds-eye view furnished by a well arranged plate, and when 

 illustrations are drawn to the same scale one loses the impression of comparative 

 size. It remains to be seen whether this feature will find favor with investi- 

 gators, c. J. c. 

 Schwendener, S. Gesammelte botanische It is very fortunate for botaniststh at 

 Mittheilungen. 8vo. I: pp. VIII t- 453. the numerous papers published by 

 figs. IS, pi- II- Vol. II. pp. VI -I- 419. figs. ^,,01 1 J • 4-1 

 8, pi. 15. Berlin: Gebnider Borntrager, Prof. Schwendener durmg the past 



189S. M25. twenty years, in the Berichte and 



Abhaudliingcn of the Royal Prussian Academy of Sciences, and other places, 

 have finally been brought together in convenient form. The papers are 

 arranged according to subject and the contributions on each subject are arranged 

 in chronological order. The subjects treated in the first volume are : trajectory 

 curves ; stomata ; phyllotaxy ; ascent of sap ; swelling and double refraction ; 

 twining of plants. In the second volume the subjects are : stability of plants ; 

 growth; latex vessels; protective sheaths; pulvini. The volume closes with 

 two papers by Schwendener and Krabbe. 



Most botanists believe that a reduction 

 Stevens, Wm. C. Ueber Chromosomentheilung ,. . . ^ 1 1 r wi • 



bei der Sporenbildung der Fame. lier. d. division of the chromOSOmeS (in WeiSS- 



deutsch.bot. Gesell. 16: 261-265. pi. 15, 1898. mann's sense) does not occur in plants. 

 Guignard, Strasburger, Sargant, Mottier, and many others have found that there 



