26 SUMMARY OF CURRENT RESEARCHES RELATING TO 



b. Histology. 



Intercellular Connections in Fowl's Egg.* — E. A. Andrews 

 describes bridges of clear protoplasm passing from cell to cell across the 

 cleavage furrows of a young blastoderm, and between cells in the super- 

 ficial layer and deep-lying cells. Whether in the normal living blasto- 

 derm of the fowl's egg there are such cell-connections, and whether 

 they serve to establish physiological communication, remains to be 

 demonstrated, but the supposition that such phenomena are general 

 seems increased by this case. 



Microbioids of the Purple Gland of Murex brandaris. f — R. Dubois 

 obtained in an alcoholic extract of this gland peculiar doubly refractive 

 droplets like Lehmann's " cells " ; they can give rise spontaneously to 

 " musculoid " fibres. They go through " une veritable evolution," 

 becoming more regularly spheroidal, acquiring a nucleus and a nucleolus, 

 and they develop reddish-brown pigment. They give off pseudopodia 

 (or should one not say pseudo-pseudopodia ?) with apparent spontaneity. 



Matrix Tissue. J — F. K. Studnicka describes various forms of 

 " Grundsubstanzgewebe," or matrix tissue : — The- young dental papilla 

 in Selachians, the corium and mucus-cartilage of Ammocoetes, the 

 corium and subcutaneous gelatinous layer in the lancelet and Lophius, 

 the pericerebral tissue in Lophius and Ophidium, and the gelatinous and 

 hyaline tissue in the skeleton of Lophius and Orthagoriscus. 



The matrical substances may arise through the direct modification of 

 the protoplasm of a reticulate embryonic tissue, and may be directly 

 exoplasmic (tooth-papillae of Selachians). 



The matrical substances may arise not only between individual cells, 

 but also between cell-layers of the embryo, as if they had an intercellular 

 origin. It is highly probable that they arise from structures which 

 resemble the intercellular parts or walls of epithelium, and it is certain 

 that in these cases they are exoplasmic (gelatinous tissue of Amphioxus 

 and Lophius, supporting lamellae and some gelatinous tissue in 

 Ccelentera). 



The " Grundsubstanzgewebe " may remain without cells, growing 

 and nourishing itself independently, and forming new tonolibrils in its 

 interior (gelatinous tissue of Amphioxus and the vitreous humour). In 

 other cases it may include cells (gelatinous tissue of Lophius, sheaths of 

 the notochord). Finally, there are cases in which an originally cellular 

 matrix-tissue may secondarily lose its cells, and yet remain capable of 

 nutrition and formative processes (filling tissue in the bones of Lophius 

 and Orthagoriscus). 



Striped MuscleJ — K. Hiirthle describes some interesting observations 

 on striped muscle, made with a view of reaching some definite view as 

 to the nature of the contractile substance. We can only refer to a few 

 points. Kuhne's observation of the movements of a living Nematode 



* Johns Hopkins Univ. Circular, No. 3 (1907) pp. 9-15 (2 pis.). 



+ C.R. Soc. Biol. Paris, lxii. (1907) pp. 435-8. 



j Anat. Anzeig., xxxi. (1907) pp. 497-522 (15 figs.). 



§ Biol. Centralbl., xxvii. (1907) pp. 112-27. 



