OLIVE: STRUCTURE OF BOTRYORHIZA HIPPOCRATEAE 339 



pairs of conjugate nuclei, those of the stalk and also those of the young 

 spore, which is shown in process of abstriction. As in other cases of 

 cell-division among fungi and algae, a ring-formed constriction grows 

 in from the periphery, thus cutting off in this instance the binucleate 

 spore from the binucleate stalk cell. Fig. 9 is a drawing of such a 

 young spore, showing the two nuclei; in Fig. 10, the two nuclei have 

 fused, though it is evident from the presence of the two nucleoles that 

 this fusion has only recently taken place. Figs. 11 and 12 represent 

 mature spores, each borne on binucleate stalks, the latter figure 

 showing the apical protuberance so characteristic of most spores. 

 That this protuberance is the primordium of the apical germ-tube is 

 apparent from a perusal of Figs. 13 and 14. These spores, as is 

 stated above, germinate at once on maturity. In Fig. 14, the hetero- 

 typic nuclear division is proceeding; this, however, is so poorly stained 

 in the preparation, that it is not possible to make out the details of the 

 process. Figs. 15, 16, and 17 show the basidia, or promycelia, each 

 composed of four uninucleate cells, which result from the germination 

 of the teliospores. In Fig. 15 appears a type of germination which 

 apparently results from growth of the basidium in a very damp situa- 

 tion; the four cells of the basidia in such cases often break apart 

 and function independently. Fig. 16 shows the more usual type of 

 germination, in which each of the four cells sends out a branch, to 

 bear finally at the tip of each a single uninucleate basidiospore on a 

 sterigma. Two of these oval basidiospores are shown in Fig. 18. 



General Discussion 



It will be seen from these figures and the accompanying description 

 that while Botryorhiza undoubtedly resembles a short-cycled lepto- 

 Uromyces in the one-celled character of its teliospores, it is sufficiently 

 distinct in other respects to justify its being placed in a new genus. 

 Some of these differences are as follows: the walls of the teliospores 

 in Botryorhiza are thin instead of thickened, as is usual in Uromyces; 

 they are colorless, instead of brown or otherwise colored, as in Uro- 

 myces; there are no germ-pores in the walls of the spores of Botryorhiza, 

 whereas the teliospores of Uromyces are characterized by one or more. 

 Finally, the possession of such strikingly large, botryose haustoria, 

 so characteristic of Botryorhiza, is, in my opinion, a very distinctive 

 feature. 



Apparently the more usual type of rust haustorium, so far as our 

 few studies on the subject have revealed, is that of an irregular, 

 branching hypha. Atkinson^ has, however, figured the haustoria of 

 Uromyces caryphyllinus as somewhat irregular and botryose in form; 



* College Botany. Henry Holt & Co. P. 87. 



