250 EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 



internal aerian membrane as many small reticulated surfaces as there 

 exist polyhedric areolse between those vessels. Anatomically, this net- 

 work is composed of an uncertain number of minute branches of a third 

 or fifth of the size of the annular vessels, into which they open at 

 various points of the circumference of the area enclosed by the latter, 

 and divide into very delicate ramusculi, which are lost in a net-work of 

 still more minute capillaries of uniform size, and about y^ mill, in dia- 

 meter, and by which minute net- work the whole surface is covered. 

 These capillaries anastomose frequently with each other, and form so 

 close a texture that the spaces between them, even under high magnify- 

 ing powers, appear only as points. 



2nd. Considered as a whole. The little polyhedric spaces above 

 described anastomose with each other at their borders, and constitute 

 by their junction a vast surface of capillary net- work, occupying the full 

 extent of the pulmonary air membrane. 



Intercanalicular septa. These constitute the intervals which separate 

 the canals. 



Their thickness varies from i to i of the diameter of the canals, and 

 they are composed of two small (petites) membranes, segments of the 

 circular walls of two canals, and between them are enclosed the annu- 

 lar vessels and the minute labyrinthine canals. 



M. Dujardins " Complete Manual for the Microscopic Observer." 

 This work, which is quite original in the choice of the designs, of 

 which it is composed, and in the mode of view expressed in these 

 designs, is intended to show how the details of a great number of 

 " test objects" may be seen at the present time with the most perfect 

 microscopes ; and it is at the same time a collection of abundant mate- 

 rials serviceable for the study of the intimate structure of organized 

 bodies. The author has attempted to demonstrate by correct figures 

 the true constitution of the blood globules, or corpuscles, which when 

 deprived of external membrane, can be agglutinated, drawn out and 

 deformed in various ways under the influence of reagents ; and has 

 endeavoured to show that the nucleus which belongs only to the blood 

 globules of birds and other oviparous animals, is nothing else than the 

 first degree of alteration. He also believes that he has demonstrated 

 the true origin of the spermatozoa, or pretended spermatic animalcules. 

 He has represented the mode in which these bodies originate in the 

 mucous covering of the tubuli seminiferi, or in mucous globules, which 

 soon become isolated, and which have been mistaken for vesicles. He 

 proves also that in certain circumstances, the fibres or lamellae of the crys- 

 talline lens are transversely striated or grooved, a marked indication of 

 their contractility. The figures representing the modifications which 

 the nervous substance undergoes when in contact with water, will serve 

 to show, as the author expects, the slight foundation upon which is 

 based the opinion which admits of nervous filaments originally provided 

 with enlargements (varicose fibres). 



A great number of figures are intended to represent the true structure 

 of the muscular fibre, examined in the whole animal series, and under 

 different degrees of alteration. Hairs, scales and various epidermic pro- 



