Botany 129 



No. 269. JOHNSON, DUNCAN S. The Fruit of Opuntia fulgida. Octavo, 62 pages, 



12 plates. Published 1918. Price $1.25. 



This paper embodies a study of the occurrence and significance of certain 

 striking peculiarities in the development and fate of the persistent self-propagating 

 fruits of several Opuntias. The discussion is concerned primarily with the peren- 

 nation and vegetative propagation of the ovary of Opuntia fulgida. 



No. 140. CAMPBELL, DOUGLAS H. The Eusporangiatce: The Comparative Mor- 

 phology of the Ophioglossacea and Marattiacecs. Quarto, vr-f-229 

 pages, 13 plates, 192 text figures. Published 1911. Price $4.00. 



This memoir is a study of the comparative morphology of two orders of ferns 

 which are sometimes known as the Eusporangiatas. These are probably the most 

 primitive of living ferns, and a thorough knowledge of their morphology is essen- 

 tial for a complete understanding of many fossil types, as well as for a clear com- 

 prehension of the relationships existing between the living ferns. The object of 

 the investigations here presented was to make a thorough study of the develop- 

 mental history of as many of the living genera as could be obtained. To this end 

 extensive collections were made by the writer in various parts of the world, and 

 much of the material presented is the result of investigations made upon these col- 

 lections. Fairly complete material was secured of all but two of the living genera, 

 and the investigations include a careful study of the gametophyte and embryo of all 

 the genera investigated, as well as the structure of the adult sporophyte. 



Mb. 58. PEARL, RAYMOND. Variation and Differentiation in Ceratophyllum. Oc- 

 tavo, 136 pages, 2 plates, 26 text figures. Published 1907. Price $1.00. 



The purpose of this study was to determine, so far as possible, the biological 

 factors concerned in the production of the particular kind of frequency curves of 

 fluctuating variation observed for the plant Ceratophyllum. A detailed analysis or 

 "dissection" of the gross frequency curves of variation in terms of the individual 

 variant is made. As a result of this analysis, it is possible to give a clear and 

 definite statement of the factors which immediately determine the degree and kind 

 of fluctuating variation exhibited by the different parts of this plant. The effect of 

 environmental forces on growth and differentiation, and the relationship between 

 intra-individual, intra-racial, and inter-racial variation and correlation are con- 

 sidered. 



For other works relating to Botany, see Nos. 24 and 30 on page 97; 81 on 

 page 98; 112 on page 99; and 192 on page 131. 



