ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
319 
the structure of these and that of Bacillus caucasicus, ffliizobium, Frankia , 
and Clostridium Pasteurianum. 
With the exception of the tubercles of Lycopodium cernuum, the fila- 
ments of the parasite always enter the tissue by perforating the external 
wall of an epidermal cell. The roots thus attacked are usually, though 
not always, destitute of root-hairs. It is most commonly the younger 
parts of the roots that are attacked, but the position of the tissue chiefly 
infected differs in different cases. The intercellular spaces may also be 
attacked, or may be left free. The attacking kyphse are in some cases 
characterised by the formation of “ vesicles,” apical swellings which 
appear to assist in their penetration of the tissues. Within the cells of 
the internal layers of the infected tissues, they also form bodies which 
the author terms “ sporangioles,” globular structures varying in diameter 
from 2 • 5 to 23 /*,, filled at first with a hyaline substance which subse- 
quently becomes granular, and is composed of spherical corpuscles, which 
he designates “ spherules,” varying between 1 * 5 and 6 p in diameter. 
The author regards the connection of parasite and host as one of true 
symbiosis, the parasite furnishing to the host nitrogenous food-materials, 
which it obtains by assimilating the free nitrogen of the atmosphere, 
while it receives protection in return, as well as food-material in the 
form of carbohydrates. It is in fact a facultative aerobe, which pene- 
trates living tissues for the purpose of avoiding oxygen. 
Laboulbeniaeese.* — Mr. B. Thaxter publishes a monograph of this 
remarkable family of Fungi, belonging to the Ascomycetes, but display- 
ing singular affinities with the Floridem. They are all parasitic on 
living insects, mostly aquatic, and are for the most part American. Of 
the 28 genera only 9 have at present been found in the Old World. 
The genera are arranged in two groups — the Endogenee, in which the 
antherozoids are formed endogenously in antherids, 26 genera ; and the 
Exogenas, in which the antherozoids are formed exogenously, 2 genera. 
The Endogense are again divided into the Peyritschielleae, 11 genera, with 
compound antherids, and the Laboulbenieae, 15 genera, with simple an- 
therids. Each of these orders includes monoecious and dioecious genera. 
The main body of the fungus is usually quite simple in structure, 
composed of several cells, and is attached by a disc-like base to the 
chitinous integuments of the insect ; there is no mycele in the body of 
the host. Towards the summit of the filament are filamentous appen- 
dages which bear the antherids ; lower down is the procarp, a multicel- 
lular structure containing a carpogenic cell, and bearing a trichogyne. 
After fertilisation the carpogenic cell divides several times, and develops 
the asci ; while these are being differentiated, the sterile cells of the 
procarp form the wall of the perithece. The perithece is usually a flask- 
shaped body, opening by a pore at the apex, and resembling in many 
respects the cystocarp of the Florideac. The ascospores are usually dis- 
charged in pairs from the perithece. The antherozoids (pollinoids) are 
very minute, and are often rod-shaped ; they attach themselves in large 
numbers to the trichogyne, but the actual fusion has not been observed. 
The trichogyne may be simple or much branched, and may consist of a 
* Mem. Amer. Acad. Arts and Sci., xii. (1896) pp. 187-429 (2G pis.). See Bot. 
■Gazette, xxiii. (1897) p. 216. Cf. this Journal, 1896, p. 218. 
