ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
515 
spore, and the process must, therefore, be regarded as only imperfectly 
sexual. It occurs in many species of Synedra, in Bhabdonema arcuatum , 
and in Achnanthes subsessilis. In the second type two auxospores are 
formed from four daughter-cells resulting from two mother-cells. It has 
been observed in many species, and is the prevailing one in the “ pennate 
diatoms.” A further advance in sexual character is exhibited by the third 
type, where one auxospore is formed directly by the union of two mother- 
cells ; it has been noted in species of Cocconeis, Eunotia, Cymatopleura , 
Surirella , and Auricula. The fourth type, a purely non-sexual one, 
where one auxospore results from a single mother-cell, appears to be 
the sole one in the group of “ centric diatoms,” e.g. Melosira and many 
others. 
Derbesia and Eryopsis.* — Herr E. Kiister has investigated the 
nature of the spherical colourless bodies which are expelled with con- 
siderable force when a living tube of Derbesia Lamourouxii is wounded. 
They are very numerous — from 50 to 200 from a single tube — and 
vary greatly in size ; the author finds them to possess all the properties 
of true sphero-crystals. Similar results were obtained with Bryopsis , 
but not with any other of the genera of Siphon eae. The protoplasm 
of a Bryopsis- tube, when injured, is transformed partly into doubly 
refractive sphero-crystals, partly into a solid amorphous substance. 
Herr Kiister believes this to be the only recorded example of the 
formation of sphero-crystals as the result of a disorganisation of proto- 
plasm. 
Fungi. 
Fungi which attack Timber. f — Herr F. Ozapek confirms the 
observations of Miyoshi J and Marshall Ward,§ that the hyphm of 
certain fungi have the power not only of perforating wood, but of con- 
suming the stores of starch and other food-material. He succeeded, in 
the cases of Pleurotus pulmonarius and Merulius lachrymans , in extract- 
ing the enzyme by means of which the lignified walls of the cells are 
destroyed, and proposes for it the term Tiadromase , in contradistinction 
to the cytase which consumes the cellulose. 
Biology and Cytology of Achlya.|| — Mr. A. H. Trow finds, on flies, 
a species of Adilya which he regards as a variety of the American species 
americana. A study of its life-history has led to the following general 
conclusions. 
The nucleus is bounded by a nuclear membrane, and possesses a 
central body of spongy texture, which contains chromatin and nucleolar 
matter, but is neither nucleole nor chromosome. The space between 
the nuclear membrane and the central body is occupied by nucleo-hyalo- 
plasm, and is traversed by fine threads of linin. The nucleus undergoes 
divisions in the mycele, and the nuclei produced in this way pass into 
the sporanges and gametanges. Neither nuclear divisions nor fusions 
take place in the sporange, nor any nuclear fusion in the gametange. 
* Ber. Deutsch. Bot. Gresell., xvii. (1899) pp. 77-84 (1 pi.). 
t Tom. eit., pp. 166-70. 
X Cf. this Journal, 1896, p. 92. § Cf. this Journal, 1898, p. 660. 
|| Ann. of Bot., xiii. (1899) pp. 131-79 (3 pis.). Cf. this Journal, 1896, p. 216. 
