108 The Plant World. 



morphologw This was especially the case in etnbryological 

 in\es'tigations, where free-hand sectioning had been practically 

 universal among botanists up to about 18S.T. The adoption 

 of the microtome in the botanical laboratories of America soon 

 resulted in the solution of many very difficult i)roblems, such as 

 the develo])ment of the juothallium of the heterosporous 

 Pteridophytes and the minute details in the historv of the 

 embryo-sac and embryo of the seed-plants. 



The study of the gametopliAte in the seed-plants has been 

 a favorite theme with American Ijotanists. In this province the 

 influence of the strong botanical department of the University 

 of Chicago has been very great. The long series of papers on 

 both Gymnosperms and Angiosperms, written b\" members 

 of the staff or by students working in the Hull Botanical Labora- 

 tory, and many other j^apers prepared b}- students trained in 

 Chicago, make one of the most important contributions to mor- 

 phology that this countrv has prf)duced. 



First in importance of the work of the Chicago botanists 

 has been the series of investigations upon the Gvmnosperms, 

 especially the papers dealing witli the Cvcads. The striking 

 discovery of spermatozoids in Cycas and Ginkgo by the Japanese 

 l)otanists, Ikeno, and Hirase and those of Zamia, discovered by 

 Webber in America, aroused renewed interest in the develop- 

 ment of the Gymnosperms, and this was especially the case in 

 Chicago where the results of many vears of special investiga- 

 tions were finally embodied in the admirable treatise on the 

 G)^mnosperms recently jniblished by Professors Coulter and 

 ChamV)erlain. Other inxestigators who have interested them- 

 selves in the morphological stud}- of the Gymnosperms are 

 Coker, Miss Ferguson, Jeffrey, Pawson, Penhallow, vShaw, and 

 Webber. 



The number of investigations on the development of the 

 Angiosperms, especially those dealing with the structtires of 

 the embryo-sac, has been very large. Particular interest has 

 been shown in the ([ucstion of the homologies of the embryo- 

 sac structures, and a search for forms which connect the pre- 

 vailing type with more ])rimitive ones. Of the manv contribu- 

 tors to this important subject, the following investigators may 



