ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 795 



Diatomee riproduconsi per germi " * (" New Arguments to prove 

 that the DiatomaceEe are reproduced by Germs "), and the other, 

 " Osservazioni e note a elucidazione dello sviluppo delle Diatomee " \ 

 (" Observations and Notes to elucidate the Mode of Development of 

 the Diatomacete "), I have referred with details to two gatherings 

 which I obtained and examined. The first contained only Pinnularia 

 stmironeiformis Sm. var. latialis, the other only innumerable frustules 

 of Gyclotella pisciculiis Ehr. ; the largest and the smallest valves of 

 the two species compared together gave an identical fineness of the 

 stria3. I have made this year, and with the same result, similar 

 examinations of different species of diatoms from the first Century of 

 the typical preparations of Dr. Eulenstein, particularly Navicula 

 Jennerii Sm. (Scoliopleura tumida), Navicula {^Pinnularia) major Kz., 

 Isthmia enervis Ehr., and Navicula didyma Kz., on a preparation by 

 Bourgogne. After results so concordant, it does not seem to me 

 possible to doubt that, at least in these species, the fineness of the 

 striae is the same on valves of different dimensions, that is to say, 

 that the fineness of the stride is determined by the idiosyncrasy itself 

 of the species, and consequently that, in accordance with Smith's 

 opinion, the striae and their fineness are a quality of specific 

 importance. 



Finally, to better convince those who have a contrary opinion, and 

 to prove that the number of the stride remains constant in large or 

 small diatoms, provided that they belong to the same species, and 

 that consequently we cannot refuse to the number of these strias the 

 value of a specific character, I will refer to the fact that in the 

 above-mentioned Century there is a very fine preparation of Isthmia 

 enervis Ehr., in situ, on which the frustules adhere to one another by 

 the angles and are attached to the pedicel. The same pedicel bears 

 large and small frustules united together, so that no more favourable 

 occasion could have been found to test the matter. I then produced 

 with the usual amplification the frustules of extreme dimensions, and 

 measured the lines of small granules on the bands or zones on the one 

 and on the other, and I did not find the least difference in the 

 numbers. I think, therefore, that it is not possible reasonably to 

 maintain the least doubt. If, however, any observer prefers to rely 

 on his own verification, nothing would be more agreeable to me, for 

 I shall then see my assertions confirmed independently. 



In speaking above of Eunotia formica Ehr., I have referred to the 

 characteristic peculiarity of this very interesting species, that is, that 

 the moniliform striae are distributed in an irregular manner and are 

 peculiarly grouped and close at the two extremities and wide in the 

 intermediate parts. By this observation I have shown that I do not 

 consider the character of the striae and their number as a character of 

 an absolute specific value, but that I admitted this value only when 

 the distribution of the striae on the surface of the valve is regular, a 

 condition which is presented in most cases, as in the Naviculce, the 

 Synedrce, and many others. But there is still another consideration 



* Atti Aecad. Pontif. Nuov. Line, 19th Marcb, 1876. 

 t Ibid., 22nd January, 1877. 



