ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 623 



In the Gentianoideae the ovular integument becomes gradually absorbed 

 from within, the external layer alone persisting to form the testa ; in 

 some Gentians the antipodal cells have a digestive function. In the 

 Menyanthoidea) absorption takes place at first outwards from the most 

 internal layer (tapis) which seems to exercise a digestive part on its 

 neighbours, itself remaining intact till an advanced stage of develop- 

 ment is reached. The absorption of the integument is less complete 

 than in the other tribe ; in Menyanthes foliolata the testa comprises 

 fifteen layers of hard pitted cells. The single layer which forms the 

 seed-coat in the Gentianoideae shows numerous structural modifications. 

 The author's researches confirm the previous opinion, based on mor- 

 phological and biological characters, and on the anatomy of the vegetative 

 organs, that the Gentianaceae fall into two well-marked subfamilies 

 Gentianoideae and Menyanthoideae. 



Abnormal Flowers of Helenium autumnale.* — W. C. Worsdell 

 gives the results of his examination of a number of abnormal heads of 

 this autumn-flowering composite, and discusses the morphological bear- 

 ing of the facts elicited. The abnormalities were due to a leaf -like 

 development (virescence) of the various floral members associated with 

 a proliferation of the axes. Pappus, corolla, stamens, and carpels were 

 all replaced in various degrees by green leafy structures. The cause of 

 the abnormal growth was presumably clue to the stimulation of a tiny 

 Phytoptus which was found in the aberrant flower-heads. The author 

 insists on the importance of such sports as aids in the solution of 

 problems in morphology. 



Fauth, A. — Beitrage z. Anatomie u. Biologie der Friichte u, Samen einiger ein- 

 heimischer Wasser- und Sumpfpflanzen. (Anatomy and biology of fruits and seed 8 

 of soine endemic water and marsh plants.) 



Beih. z. Bot. Centralbl. Orig. Arbeit, XIV. (1903) pp. 327-73 (3 pis.). 



Physiology. 

 Nutrition and Growth. 



Nitrogenous Metabolism in Minute Algae.f — Harriette Chick 

 describes a new species of Chlorella, a unicellular green alga, C. pyrenoi- 

 dosa, which differs from 0. vulgaris in having a conspicuous pyrenoid. 

 It occurs in sewage, and was also found to have grown in dilute 

 ammoniacal solutions. The author has studied its nitrogenous 

 metabolism in a series of cultures and finds that it prefers to have its 

 nitrogen presented to it in the form of ammonia or ammoniacal com- 

 pounds ; among the latter, urea, uric acid, &c, rank high in nutritive 

 value. It appears also that the ammonia after being absorbed is 

 elaborated into albuminoid ammonia. The presence of glucose in a 

 culture liquid causes a definite change in the chlorophyll-body and a 

 general stimulation of growth. A similar effect has been noted by other 

 observers in three other simple green algae, including a species of Chlorella. 



P. G. Charpentier % has studied the method of assimilation of 



* Journ. Roy. Horl. Soc, xxvii. (1903) pp. 943-55, 10 figs, in text, 

 t Proc. Roy, Soc, lsxi. (1903) pp. 458-76 (1 pi.). 

 % Ann. Inst. Pasteur, xvii. (1903) pp. 321-34. 



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