284 PROGRESS OF MICROSCOPICAL SCIENCE. 



The South African Diamonds. — Mr. G. C. Cooper, who may be said 

 to be " to the manner born," as he comes from the African diamond- 

 fiehls, has an interesting paper in the last volume of the ' Proceedings 

 of the Geologists' Association' (Oct., 1874), on this subject. Besides 

 other matters of non-microscopical interest, he says: — "I have 

 recently received a piece of what is termed ' chalk ' by the diggers, 

 which, from microscopic observations, I would infer to be in all 

 essential jjoints the same as the tufa that is so abundant, with this 

 exception, that this has been broken u]), disintegrated, as on a beach, 

 and thus made into a softer form, after its deposition as tufa. It gives 

 the same white streak as ordinary chalk. It has imbedded in its 

 surface some sand granules,j and black crystals, resembling, and, as 

 I think, the same as occurs in a sample of stuff lately given to me, 

 from 80 feet depth. Its component particles are crystalline and trans- 

 lucent, and from odVo ^^ toVo" ^^ ^^ ^^^^ ^^ diameter. Dissolves in 

 dilute muriatic acid, with some flocculent deposit. Upon evaporation, 

 star-like masses of crystals form. I look upon this specimen as of 

 importance in helping to substantiate what I advance in relation to 

 water and ice in producing the diamond deposit." 



27(6 Structure of the Testicle. — A good paper on this subject is that 

 done by Dr. Victor v. Mihalkovics, and the results of his researches 

 appear in the last part of the ' Arbeiten,' or " work done " in the 

 Physiology Laboratory of Ludwig, at Leipzic, in 1873. The conclu- 

 sions at which Dr. Mihalkovics has arrived, which j)artly agree with 

 and in part differ from those of jDrcvious observers, aie given in the 

 following manner by the ' Lancet ' (Oct. 10) :— In the first place, he 

 finds, in ojiposition to the greater number of authors, as Miiller, 

 Krause, Beale, Sappey, Kolliker, v. Luschka, and Lavalette St. George, 

 that the tortuous terminal or j^eripheric portion of the tubuli semi- 

 niferi forms a plexus by the anastomoses of their numerous dichotonous 

 divisions. The ultimate branches appear to be connected by looj^s. 

 In man, the canals in the cortical layer present small bead-like pro- 

 jections of the wall, and never begin, as most of the above-named 

 authors contend, by closed free extremities. In regard to the structure 

 of the walls, he believes Henle is most exact in stating that it consists 

 of a series of laminae, or membranes with flat nuclei. The size of the 

 tubuli bears no relation to that of the testis, since in the guinea-pig 

 it is 0*10; the cat, 0*11 ; in the cock, 0'12; mouse, 0*15; rabbit, 

 0-20; goat, 0-20; man, 0-21; dog, 0-25; bull, 0-26; and rat, which 

 is the largest of all, 0*40 of a millimetre. Secondly, the straight 

 portions of the tubes, or vasa recta, are not direct continuations of the 

 tortuous portions, but are of very much smaller diameter, and are 

 lined by a much shorter columnar epithelium. They run in the con- 

 nective tissue of the corpus Highmorianum or in the lowest parts of 

 the septa. Thirdly, the supporting cells, described by v. Merkel, and 

 germ plexus are, he thinks, artificial products, which owe their exist- 

 ence to the coagulation of a tenacious albuminous substance occupying 

 the interspaces between the seminal cells. Fourthly, certain inter- 

 stitial cells are constituents of the testis, the analogues of which are 

 discoverable in many other organs, as the supra-renal capsules, the 



