398 SECTIONAL TRANSACTIONS.— K. 



hymenial patches bear pigmented spores, while those of the lighter patches 

 do not. 



The hymenium of I'<ulIiota campcslris consists of basidia and paraphyses. 

 The paraphyses are permanently sterile elements. The basidia on any one 

 small portion of the hymenium can be classified as past-generation basidia, 

 present-generation basidia, coming-generation basidia, and future-generation 

 basidia. 



11. Dr. Malcolm Wilson. — The Cytology and Life-history of Tuhur- 



cinia. 



The two British species of Tuhurcima show considerable differences. 



In T. qn'unuUcola the mycelium, which is perennial in the rootstock, pene- 

 trates the entire plant, and produces conidia on the stamens. These conidia 

 may be distributed, along with the pollen, by insects. They are unicellular 

 and often conjugate in pairs, the united conidia then giving rise to a secondary 

 conidium which may grow out into a germ-tube. Chlamydospores are found 

 between the ovules in flowers which previously produced conidia. The chlamydo- 

 spore masses germinate as soon as free, each spore producing a germ-tube 

 which bears a whorl of 3-5 primary sporidia. These occasionally conjugate in 

 pairs, but generally each produces a secondary sporidium without conjugation. 



In T . Tricntalis certain infected rhizomes produce shoots which bear stalked , 

 conidia on the under surface of the leaves. These conidia may form secondary j 

 conidia without conjugation. 



The plants bearing conidia also produce chlamydospores in the cortex andl 

 pith of the stem. These germinate in the late autumn, each spore producing 

 a germ-tube which bears a whorl of 8 primary sporidia. Conjugation takes place 

 regularly between the primary sporidia ; secondary sporidia are produced, and 

 these on germination may bring about the infection of the rhizomes. 



In T. primulicola the cells of the perennial mycelium are generally uninu- 

 cleate. The conidia are uninucleate, and during conjugation a nucleus passes 

 from one conidium into the other. The secondary conidia are binucleate. Thesel 

 presumably give rise to the mycelia consisting of binucleate cells. There is a 

 nuclear fusion in the young chlaraydospore, the mature spore being uninucleate. 

 The primary sporidia are generally binucleate, occasionally uninucleate. The 

 secondary sporidia are sometimes binucleate, sometimes uninucleate. 



In T. Trientalis the mycelium present in the host plant consists of binucleate 

 cells. It has been impossible yet to determine the nuclear condition of the 

 chlamydospores and sporidia. It may be concluded that in T. primulicola the 

 conjugate nuclear condition is brought about during the conjugation of the 

 conidia. In T . Tricntalis it is suggested that the conjugate condition is produced 

 at the fusion of tlie sporidia. 



12. Miss K. B. Blackbuen and Dr. H. Harrison. — The Meiotic 



Phase in the Salicacece. 



The cytological behaviour in the Salicacece is not in any way comparable 

 with that of the genus Eosa ; the majority of the species of both genera show 

 perfect reduction divisions. When, however, this fails, as, for example, in 

 Salix fragilis, the phenomena observed resemble the conditions seen in the 

 hybrid Oporahice. 



The fundamental chromosome number in both Salix and Populus is 19, 

 although many species of Salix are tetraploid, and at least one is hexaploid. 



'Somewhat unexpectedly, in the homogeneous Caprece group the species do 

 not agree as to the haploid number of (chromosomes, 6'. aurita and S. cinerea 

 being characterised by 38 and S. Cajjrea, in the main, by 19. 



Compound chromosomes occur both in Salix and Poputus. and some evidence 

 exists of the presence of an unequal chromosome pair in the male plants. 



A metamorphosans variety of S. Caprea was examined, and displayed the 

 number of chromosomes proper to the species. 



13. Mr. W. C. F. Newton. — Somatic Chromosomes. 



The somatic divisions have been studied in several Spermatophyta, and 

 the pairing of the allelomorphs and the longitudinal fission of the chromosomes 

 differentiated. 



