TRANSACTIONS OF SECTION K. 849 



a syatem in which we express the limitations of our knowledge, as we suit our 

 convenience, by dividing into periods the history of geological and organic 

 evolution. 



' It is only our ignorance that fixes a limit, as the mist gathered round the 

 mountain's brow makes us fancy we are treading the edge of the universe.' 



The following Reports and Papers were read : — 



1 . Report of the Committee on the Teaching of Botany in Schools, 

 See Reports, p. 420. 



2. Report of the Committee on the Investigation of the Cyanophycece, 



See Reports, p. 419. 



3. Report of the Committee on Botanical Photographs. 

 See Reports, p. 416. 



4. Report of the Committee on the Respiration of Plants. 



5. The Dcvelojrment of the Ascocarp in Ryjyarobius. 

 By B. T.P. Barker, M.A. 



Pure cultures of a species of Uyparobius, occasionally found on wild-rabbit 

 dung, were obtained from a single ascospore. The fungus grows vigorously on 

 many artificial nutrient media, rabbit-dung, carrot, and potato. No true conidia 

 lire formed, reproduction being carried on by ascospores. The ascocarps are 

 usually developed in old cultures, but their development step by step has been 

 observed under the microscope in hanging-drop cultures from a portion of 

 vigorously growing mycelium, suddenly starved by transference from beerwort to 

 distilled water. The archicarp consists of a small coiled hypha, the ascogonium, 

 and a slender hypha, arising from the next cell of the mycelium, and growing 

 over to the tip of the ascogonium, which appears to be an antheridial branch. 

 Fusion probably takes place. The ascogonium then divides into a number of 

 cells, which branch, and eventually produce a varying number of asci. A pseudo- 

 parenchymatous tissue is formed around the ascogonium by the growth of 

 investing hyphse, arising from the neighbouring cells of the hypha which bears 

 the archicarp. This tissue forms the wall of the ascocarp. The ascogonium 

 appears to be uninucleate at first, and immediately after contact with the anthe- 

 richal branch contains two nuclei, either sitvxated closely together or apparently 

 fusing. Later most of the cells of the system of hyphae, developed from the 

 ascogonium, are uninucleate, but some contain two nuclei, which probably fuse 

 and become the single nucleus of a young ascus. The ascus becomes multi- 

 nucleate, the nuclei arrange themselves just beneath the wall of the ascus in the 

 form of a hollow sphere, and the ascopores are then formed, each with one end 

 pointing towards the centre and the other towards the wall of the ascus, the 

 arrangement thus being radial. Very little periplasm is present in the zone of 

 spore formation. Associated closely with the single nucleus of the young ascus 

 is a structure of variable shape which has almost as strong an affinity for stains 

 as the chromatin of the nucleus itself This structure appears to be of the 

 1903. 3 I 



