ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 781 



gencous, while the thicker inner one is made up of several super- 

 imposed layers; the striking difference between the chemical reactions 

 of the two is pointed out, and the differences in their appearance 

 and structure detailed ; to see them best the cuticle of the proboscis 

 should be examined after maceration. 



Dermal projections of various kinds are found on different parts 

 of the body ; the simplest are the papillae which are found irregularly 

 distributed on the rings of the trunk; they are blunt conical projec- 

 tions about • 1 mm. long, are invested by a thin cuticle, and filled by 

 a process of the hypodermis ; the cells of the latter form a continuous 

 layer, with the exception of the central portion where there is a mesh- 

 work of nucleated fibres. The papillae on the hinder edge of the 

 last ring are not only distinguished by their greater length, but by the 

 presence within them of a wide -meshed network of extremely fine 

 fibres. Modified dermal papillae are to be found on tbe costae of the 

 proboscis, where they form conical projections, the two lower thirds of 

 which are invested in a kind of shield. 



The description of the costae of the proboscis given by Koren 

 and Danielssen is stated to be incorrect, the glands described by them 

 being merely integumentary canals cut across. Beneath the integu- 

 ment, and between it and the musculature there is at the anterior end 

 of the body a space which communicates with the body-cavity by the 

 intervals between the muscular bands. 



Especial attention may be directed to the fact that for its whole 

 length the nervous system is in connection with the ectoderm ; it is 

 essentially composed of extremely delicate fibrils covered by thicker 

 fibres united into a plexus and passing into the cells of the hypodermis. 

 Some corrections are made in the account given by the original 

 describers of the female genital organs, and the male organs, which 

 were not described by them, are stated to have the same form and 

 position as the female, but instead of a lamellar they have a racemose 

 structure, and the efferent duct is not suj)erficial but principally 

 internal. The nuclei of the cells were of considerable size, and the 

 finely granular contents are divisible into a cortical and a medullary 

 portion. 



Anatomy of Ankylostoma duodenale.* — W. Schulthess gives a 

 detailed description of this Nematoid, the length of which has been so 

 very variously stated by different authors ; the present investigator 

 finds it to vary from 6 to 18 mm. After an account of the external 

 form and the differences between the males and females, the writer 

 passes to the integument, the two layers of which are described ; in 

 the study of the muscular layer we may distinguish the longitudinal 

 lines, the muscles, and the papillae ; in dealing with the last, attention 

 is directed to two hitherto undescribed structures ; on the ventral 

 surface of the male the skin, at one point on either side, is traversed 

 by a fine subcuticular tissue, while in the female two similar struc- 

 tures are to be found near the tip of the tail ; the significance of these 

 bodies is only incompletely understood. The digestive tract is divisible 



* Zeitschr. f. wiss. Zool., xxxvii. (1882) pp. 163-220 (2 pis.). 

 Ser. 2.— Vol. II. 3 G 



