( 3-^ ) 

 PEOaRESS OF MICROSCOPICAL SCIENCE. 



The Spermatozoa ofPetromyzon. — Mr.George Gulliver, F.R.S.,says:* 

 " 111 my paper ' On certain Points in the Anatomy and Economy of the 

 Lampreys,' published in 1870, f there is an engraving of the sperma- 

 tozoa of Petromyzon planeri. But I know not that those of P. marinus 

 have ever been described or depicted ; and they differ curiously in the 

 two species. The spermatozoa of P. marinus, notwithstanding the 

 great size of the species, are much the smallest, and have a distinct 

 and rounded head. Their mean length is about 40^^77 inch, and their 

 thickness 48^o~o. They were obtained from a fish thirty-two inches 

 in length and three pounds in weight, taken on May 12, 1874, in the 

 river Stour, near Sturry Mill, about two miles below Canterbury. 

 The milt, which distended the whole abdomen from the pericardium 

 to the anus, was a soft pulpy mass chiefly composed of a creamy 

 semen, and so rich in and crowded with spermatozoa of such minute- 

 ness that they were with difficulty distinguishable ; and it was not 

 before the semen had been much diluted and placed under Powell and 

 Lealand's jV^^ objective that a good view of them was obtained. Under 

 a lower power, especially in the pure semen, nothing more than con- 

 geries of indistinct rounded points appeared, like those which I have 

 described in the ' Proceedings ' of this Society i as the ' molecules of 

 the semen.' In short, unless great care be taken, the spermatozoa in 

 the ripe testis are so very faint, minute, and abundant, that they are 

 likely to escape detection. But the spermatozoa of the little Petro- 

 myzon planeri are much larger and more easily seen. They are club- 

 shaped, without a distinct head, and have an average length of o^V^ 

 inch, and a thickness of ^tj^q-q-. They were obtained in April from 

 a fish six inches in length and two drachms in weight. Further 

 details concerning the generative organs of both sexes are given in 

 the paper first quoted in the present communication." 



The Leaf Glands of Saxifraga tridactylites. — An addition to our list 

 of carnivorous plants is suggested by Mr. J. C. Druce in a letter to the 

 ' Pharmaceutical Journal,' in a little early spring flower found chiefly 

 on the tops of walls, Saxifraga tridactylites, a plant not very distantly 

 allied to the Droseras. Mr. Druce states that when examined under 

 the microscope the leaves are seen to be covered with glands of a 

 similar character which exude a viscid secretion, in which he found 

 a midge was entrapped and held fast when placed on the leaf. On 

 examining a number of leaves, he found in all of them the debris of 

 insects which had aj^parently perished in this manner. 



Presence of Micrococcus and Bacteria in the Walls of Hospital 

 M^ards. — The analyses of the air, and other exj)eriments made by 

 Pasteur, for the purpose of investigating the doctrine of spontaneous 

 generation, have demonstrated that the germs of inferior organisms 

 — micrococci, bacteriae, &c. — are everywhere present in the air. In 



* 'Proceedings of the Zoological Society.' f Ibid., 1870, p. 844:. 



X ibid., 1842, p. 99. 



