ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 643 



contents finally lie as granules in clear vacuole-like areas. The eggs are 

 formed during this process of degeneration. The protoplasm is arranged 

 around a large central vacuole ; the ooplasm collects round several 

 centres each of which will become an egg-origin. The differentiation of 

 the egg-origins takes place around a deeply stained protoplasmic body, 

 the coenocentrum which is formed de novo, one for each egg-origin. The 

 coenocentrum becomes less distinct during the ripening of the egg and 

 finally disappears ; it is probably the morphological expression of 

 dynamic activities in the oogonium when the egg-origins are differ- 

 entiated, and is a sort of focal point of the metabolic processes peculiar 

 to oogenesis. They exert a chemotactic influence on any nuclei in its 

 immediate vicinity. Generally one nucleus comes to lie very close to 

 the coenocentrum ; this favoured nucleus increases in size when all other 

 nuclei in the egg-origins and young eggs are degenerating. Sometimes 

 two or even three nuclei may lie sufficiently near the coenocentrum to be 

 saved from degeneration, and such eggs become bi- or trinucleate. As 

 the eggs mature the favoured nucleus increases, becoming many times 

 larger than at the period following the mitosis. The other nuclei have 

 generally become quite disorganised, but sometimes traces remain as 

 granules scattered in the cytoplasm. The author's results show that 

 binucleate eggs in the Saprolegnias need have no relation to the problem 

 of sexuality. His work on the sporogenesis gives a general confirmation 

 of the accounts of Rothert, Hartog, and Humphrey. The uninucleate 

 spore-origins are differentiated by clefts that push them away from the 

 central vacuole of the sporangium to the periphery. When the clefts 

 reach the cell-wall the turgor of the sporangium is relieved by the escape 

 of water, and spore-origins run together, but soon draw apart again and 

 become rounded off as zoospores. There seem to be no cytoplasmic 

 centres in the sporangium comparable to the coenocentra. 



Cultivation of Truffles.* — Louis Matruchot has succeeded in 

 germinating the spores of Tuber melanosporum and of T. uncinatum. 

 He sowed them on sterilised slices of potato to which was added a 

 nutritive medium, and obtained in both instances a copious white 

 mycelium, which in a short time became brown, similar to the mycelium 

 that is to be found in truffle beds, and otherwise identical with it in 

 appearance. The author considers that the possibility of easily producing 

 this mycelium may have an important bearing on the culture of truffles. 

 The mycelium formed sclerotium-like bodies in the culture-tubes which 

 were probably undeveloped truffles. 



Raphael Dubois f reports that in order to induce the germination of 

 truffle-spores, he infected the living rhizome. A plentiful mycelium 

 was produced which he has kept growing and finally buried at the foot 

 of some oaks. Final results are not yet attained. 



Louis Matruchot % furnishes a description of the different mycelia 

 obtained by him from the culture of truffle spores. He has not 

 obtained any conidial forms. 



Emile Boulanger % records some curious observations on the 

 germination of truffle-spores. He worked with Tuber melanosporum. 



* Comptes Rendus, cxxxvi. (1903) pp. 1099-1101. 



t Tom. cit., p. 1291. J Tom. cit.. pp. 1337-38. 



§ 'Germination de l'ascospore de la Truffe,' Paris, 1903, 20 pp. (2 pis.). 



