ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 947 



may further itself break up into smaller elements, karyozoa and 

 plasraozoa, which play an important part in all tissue formation. The 

 cytozoon is the fundamental element ; the formation of embryonic 

 layers, and the differentiation of sex are explicable in terms of cytozoon 

 modifications. These speculations are further developed. 



When considered per se the cytozoa are comparable to the sexual 

 elements of filamentous fungi. Their mycelium is the nigrosino- 

 philous protoplasm, their kyphte the chromatin threads of the nucleus, 

 their gyniosium the plasmosoma ! But the development of the fungus 

 is never completed in the tissue-cell, the individual-cell is imperfect ; 

 for its completion the cell of another tissue is necessary. On this 

 the life of the whole organism depends. Prof. Gaule asserts that his 

 views are supported by numerous physiological facts, and he finds a 

 key to the understanding of organic structure in his theory of the 

 import of the cytozoa. 



Nerve-endings in the Cutaneous Epithelium of the Tadpole-* — 

 Mr. A. B. Macallum, in his second essay on this subject,! states that 

 there are two plexuses of non-medullated fibres, one wide-meshed set 

 some distance below the corium, and the other very narrow-meshed, 

 and immediately beneath the epithelium. The first may be called 

 the primary or fundamental plexus, and it sends up fibres which unite 

 with the secondary or subepithelial plexus ; from the former also 

 fibres pass up and terminate in swollen bead-like bodies between the 

 epithelial cells ; from the latter minute fibres arise which either 

 terminate within the epithelial cells, near their nuclei, or between 

 them. The fibres which enter cells of the basal and inter- 

 mediate layers of the epithelium are provided with the figures of 

 Eberth ; these decrease in size as the cells containing them show 

 fewer and fewer signs of vitality ; the figures appear, therefore, to 

 protect the intracellular ends of the nerve-fibrils from the vital 

 processes of the cells. These figures are the production of the intra- 

 cellular end of the nerve-fibrils, and are formed by or from the cell- 

 protoplasm. Free intercellular nerve-endings are due to the inter- 

 cellular fibres losing the cells with which they are connected, and 

 such are. consequently, most common between the superficial cells. 



Histology and Physiology of Ciliated Epithelium.^ — Following 

 up the experiments which Prof. Grutzuer § made upon injured ciliated 

 mucosa, in which it was seen that the injury affected only the portion 

 below the cut, Herr A. Just has studied, in the living organism, the 

 exact changes exhibited by the adjacent cells. In the pharyngeal 

 and oesophageal mucosa of living frogs, definite injuries were cleverly 

 effected by means of burning, and Grutzner's results were confirmed. 



The ciliated areas or grooves in the normal skin above the injury 

 are described and contrasted with the appearance of the adjacent area 

 below. The ciliation is stopped or checked, moribund pulsations are 



* Proc. Canadian Inst., iii. (1886) pp. 276-7. 



t See this Journal, ante, p. 218. % Biol. Centralbl., vi. (18S6) pp. 123-6. 



§ Breslauer Aerztl. Zeitschr., 1882; ' Physiologie des Fliruuierepithels,' 

 Leipzig, 1883. 



3 q 2 



