ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 21 



n 



Cytology and Physiology of Endophytic Mycorhiza. * — Shibata 

 has made additions to our knowledge of Mycorhiza in species of Podo- 

 carpus, in Psilotum triquetrum, and in Almis and Myrica. The most 

 interesting observations were those on Podocarpus, in which, according 

 to Nobbe and Hiltner, infected plants are able to assimilate free nitrogen. 

 The cells of the root-tnbercles soon become filled with masses of my- 

 celium. The cells of the host then begin to react to the presence of the 

 fungus, the cytoplasm increases and the nucleus grows in size and has 

 more stainable contents. It soon begins to divide by a process of simple 

 direct division till as many as eight nuclei may be found in a single 

 •cell. While these changes are taking place the fungus mycelium shows 

 signs of disorganisation, and not only do the contents of the hyphas be- 

 come lost, but the chitinous walls themselves become almost completely 

 dissolved. This behaviour suggests the secretion of a ferment or fer- 

 ments by the host-cell, and Shibata has actually demonstrated the presence 

 ■of a proteolytic ferment in the infected tubercles. Similar cytological 

 •observations were made on Psilotum, though here the chitinous walls 

 remain behind as an undigested mass. 



In Alnns also a proteolytic ferment was demonstrated, though the 

 symbiont in this case seems to be a bacterium-like organism. In Myrica 

 the fungus of the tubercle is confined to a definite ring consisting of 

 one to three layers of parenchyma. The radiating arrangement of the 

 hyphal branches of the fungus and the club-shaped swellings at their 

 ends point to a relationship to the genus Actinomyces. This would 

 appear to be an actual case of vegetable " actinomycosis," a condition 

 hitherto known only in animals. 



Potato Diseases.f — (Edomyces leproides, a disease of beetroots, has 

 been found on potatoes causing nodulose, black, scab-like crusts. These 

 nodules are described as containing irregularly shaped cavities which are 

 filled with the dark-coloured resting-spores of the fungus, one of the. 

 Ustilaginere. Figures of this fungus as it occurs on the potato are 

 given. A second disease, bacteriosis, due to Bacillus solanacearum, is 

 also described and figured. The leaves and stalks are attacked first ; 

 the bacteria gradually descend the stem and pass into the tnbers which 

 they destroy. 



Sclerotinia sclerotiorum attacks the potato stems, forming sclerotia in 

 the tissues and causing the death of the plant. It occurs on many other 

 herbaceous plants. 



Chrysophlyctis endobiotica,% a disease new to this country, is described 

 by M. C. Potter. The outward appearance of the tubers attacked is 

 similar to that described under (Edomyces leproides ; but this fungus 

 belongs to the Chytridinepe. The resting-spores are to be found in the 

 periphery of the nodules imbedded in the plant-tissue. Potter traced 

 it through an early plasmodium stage to the final development of the 

 thick-walled spores. 



Fungus Diseases in Italy.§ — Giovanni Briosi publishes an account 

 •of the work done in the Laboratory of Cryptogamic Botany in Padua 



• Prinp;sh. Jahrb., xxxvii. (1902) pp. 613-S4 (2 pis.). 



t Jouvn. Board nf Agric., pp. 307-11 (3 pis.). 



t Tom. cit., pp. 320-3 (1 pi.). 



§ Atti 1st. Bot. Univ. Tavia, vii. (1002) pp. 295-35G. 



