274 SUMMARY OF CURRENT RESEARCHES RELATING TO 



mutual (domatia). The former are again divided into zoocecidia, produced 

 bj animals, and phytocecidia, caused by the attacks of plants. The last 

 again include mycocecidia, due to the attacks of fungi, such as Synchyfrium, 

 and phycocecidia, e. g. the cephalodia of lichens. Domatia, again, may 

 be zoodomatia or phytodomatia ; among the former are the peculiar 

 formations on myrmecophilous plants, and acarodomatia, structures which 

 serve for the habitation of acari. Examples of mycodomatia occur in the 

 swellings on the roots of Leguminosae, and of phycodomatia in the hollows 

 in the leaves of Azolla. 



Phytoptocecidia.* — Herr F. Low describes eleven new galls produced 



by parasitic fungi on Achillea nana, AncJmsa officinalis, Galium infestum, 

 G. lucidum, Gentiana rhsetica, Lycium europseum, Buhus Gremlii, Sedum 

 album, Sempervivum liirtum, Seseli hippomarathrum, and Vitex agnus-castus. 



Parasitism of Heterodera javanica.f — Herr M. Treub has detected on 

 the roots of the sugar-cane a new species of nematode, to which he gives 

 the above name, and which is nearly allied to H. radicicola, but distin- 

 guished by its smaller size. Each gall usually contained several (female) 

 nematodes. Near the head of the parasite were always observed some large 

 cells containing a large niimber of nuclei. A similar hypertrophic effect 

 has been observed in other cases as the result of the attacks of parasites. 



Diseased Potato.^ — M. J. B. Schnetzler describes a potato of abnormal 

 form, 15 cm. long ; on its surface were four tubercules, each having 

 a diameter of five to six cm. After having been laid in a cabinet all 

 the winter, a white mould developed on its under surface, which was 

 recognized as Phytophthora infestans. On making a section of one of the 

 tubercules, the tissue was found to be overrun with the mycelium of Phy- 

 tophthora, together with a quantity of Fusisporium Solani. In the buds a 

 colouring matter, anthocyan, was found, behaving exactly like litmus with 

 acids and alkalies. 



B. CRYPTOGAMIA. 



Cryptog-amia Vascularia. 



Leaf-stalk of Ferns.§ — Herr K. Thomae has made an exhaustive ex- 

 amination of the leaf-stalk of ferns ; in reference, firstly, to the various 

 points of structure, viz. the epidermal tissue, the mechanical tissue, 

 the receptacles for secretions, the aerating system, the fundamental paren- 

 chyma, and the vascular bundles ; and secondly, to the different groups 

 into which the order is divided, viz. : — (1) Marattiacefe ; (2) Osmundacese; 

 (3) Cyathcacese ; (4) PolypodiaccEe, with its subdivisions ; (5) Gleiche- 

 niacese ; (6) Schizaeacefe ; and (7) Hymenophyllacese. 



One main result is to bring into prominence the differences between the 

 Marattiaceas on the one hand, and all the other families of ferns on the 

 other hand. In the latter there are no medullary vascular bundles ; all 

 lie, in transverse section, on a single curve, which often, in its windings, 

 approaches the centre of the stalk. Those bundles, on the other hand, in 

 the Marattiaceae which lie wathin the peripheral circle may be correctly 

 termed medullary. In the comijosition of the tissues there are also im- 

 portant differences between the Marattiacere and true ferns. 



* Verbandl. Zool.-Bot. Gesell. Wien, xxxv. (1885) pp. 451-70. 

 t Auu. Jard. Bot. Buitenzorg, vi. (1886) pp. 93-G (1 pi.). See Bot. Centralbl., 

 xxviii. (1886) p. 269. 



t Bull. Soc. Vaud., xxii. (1886) pp. 143-4. 



§ Pringsheim's Jahrb. f. Wiss. Bot., xvii. (1886) pp. 99-161 (4 pis.). 



