212 SUMMARY or CURRENT RESEARCHES RELATING TO 



allusion to its muddy habitat, was found to lack in both sexes the 

 pigmented eyes which in other Harpacticidse are so conspicuous 

 in the centre of the forehead or on either side. It is to be regretted 

 that lack of opportunity to repeatedly collect this interesting species, 

 and to endeavour to ascertain if truly pelagic species also inhabit 

 American waters, robs this discovery of much of its interest. 



Vermes. 



Mode of Application of the Suckers of the Leech.* — G. Carlet 

 has investigated this somewhat difficult matter by the use of the 

 graphic method. He finds that, if a leech be placed on a sheet of 

 smoked paper, it progresses by the alternate fixation of the anterior 

 and posterior suckers. That of the hinder one is made very simply 

 and rapidly ; the cii"cumference being first applied, and then the 

 central portion. That of the anterior is more complicated and less 

 rapid; the leech commences by exploring the place to which it is 

 going to fix itself, with the two sides of its upper lip ; the anterior 

 portion of the upper lip is then lowered, and then the lower lip is 

 applied to the surface. The pharynx begins to be lowered, and the 

 triangular contom- of the sucker gradually becomes circular. The 

 sucker then touches the paper in its centre. From these observations 

 it would follow that, instead of beginning to fix itself by the centre of 

 its sucker, and then depressing the edges, as has been generally 

 believed, it is the edges which are first applied, and the centre which 

 is last. When the leech detaches itself the edges are first raised, 

 and then the centre. 



Spermatogenesis in the Nemertinea.f — A. Sabatier finds that in 

 the Nemertinea the seminal sacs give rise to spermatospores or 

 " male ovules," composed of a mass of finely-granular protoplasm, in 

 which a nucleus may or may not be apparent. The central portion 

 of the protoplasm tends to atrophy, while the peripheral portion 

 separates from it, tends to become independent, and to form spherules 

 which become attached to the internal wall of the sac. The central 

 portion is called the protoblastophore, and the peripheral spherules 

 the protospermoblasts. In the peripheral or superficial layer of these 

 last there arise, endogenously, numerous granulations, which are 

 larger than the primitive granulations of the protoplasm. The 

 appearance of these is to be correlated with the division of the peri- 

 pheral protoplasm into small regions, which constitute the deuto- 

 spermoblasts ; and of these the central granulation and the protoplasm 

 elongate to form the spermatozoa. The central portion of the proto- 

 spermoblasts adheres to the wall of the sac, and gradually undergoes 

 atrophy and disappears ; it is the deutoblastophore. Attention is 

 directed to the exact and complete parallelism which there is between 

 the spermatogenesis of Nemertines and Annelids ; although in the 

 former we observe certain peculiarities which teach us the sig- 

 nificance of the nucleus and of the protoplasm. It is the perijjheral 

 portion alone which becomes converted into the spermatozoon ; the 



* Comptes Rendus, xcvi. (1883) pp. 448-9. 

 t Rev. Sd. Nat., ii. (1882) pp. 1G5-81 (3 pis.). 



