174 



SCIENCE-GOSSIP. 



rather as cell-products than as cells themselves. 

 Around the bacteria and Cyanophyceae, the battle 

 of nucleus or no nucleus is still warmly kept up. 

 All who have worked at this difficult subject are, I 

 believe, agreed that in the larger bacteria and 

 Cyanophyceae at least, there is a distinction 

 between a delicate peripheral layer of proto- 

 plasmic (?) substance and a large central body. The 

 matter of uncertainty is in the interpretation which 

 is to be given to this central part. Are we to regard 

 it, with Biitschli and Zacharias, as the homologue 

 of the nucleus, or, with Fischer and Migula, as 

 merely a large central vacuole ? At the present 

 state of our knowledge it is difficult to hazard an 

 opinion either way. The entire absence of the 

 ordinary parts of a nucleus such as the nucleolus 

 chromatin network, etc., has been urged against 

 the view which holds it to be a nuclear representa- 

 tive. When we regard the question, however, 

 from the standpoint of evolution, is not this 

 exactly what we should expect ? In the lowliest 

 organisms we should look for entirely undifferen- 

 tiated nuclei, and only in organisms which by other 

 signs we recognize as higher in the scale of 

 development would we expect to find nuclei show- 

 ing all the complexity of nucleolus, linin network, 

 definitely arranged chromatin granules, etc. 



To my mind the whole problem appears to turn 

 on chemical considerations. Glancing back at the 

 history of chemical cytology, it will be recollected 

 that many years ago Miescher isolated from animal 

 eells a certain material which he termed nuclein. 

 This substance has been shown to be characteristic 

 of nuclei. The recent beautiful researches of 

 Zacharias and Rosen have shown us a remarkable 

 connection existing between nuclear activity and 

 the presence of this nuclein in the nucleus. It has 

 been shown that as the power of nuclear division, 

 which is the most apparent activity of this organ, 

 gradually fades away, so in like proportion does 

 the quantity of nuclein diminish. There is some 

 reason to believe therefore that one of the necessary 

 conditions for the display of vital activity in a cell 

 is that nuclein should be present ; and all our 

 experience goes to show that nuclein is the charac- 

 teristic substance of the nucleus. When one asks, 

 therefore, whether a certain cell is nucleated or 

 not the question resolves itself into the further 

 enquiry of whether nuclein does or does not occur. 



It seems to me to be no extravagant view to hold 

 that in the simplest cell we have protoplasm in 

 which nuclein is diffusely scattered ; as phylogenetic 

 development advances the nuclein becomes drawn 

 together into a special body, and slowly as evolu- 

 tion proceeds we get produced the highly differen- 

 tiated structure we are accustomed to find in the 

 nucleus. I leave here quite out of the discussion 

 all questions dealing with the origin or significance 

 of the curious bodies known as centrosomes. 



What then has to be sought for in the central 

 bodies of bacteria and cyanophyceae is nuclein. 

 There have been found here certain granules which 

 resist artificial gastric digestion. This is one of 

 the properties of nuclein and therefore lends strong 

 probability Jp the opinion that these particles are 

 of the nature of nuclein. If a sufficient array of 

 facts can be produced to show that these grains are 

 indeed composed of nuclein, I think every justifica- 

 tion will be given for regarding these larger bacteria 

 and low algae as nucleated organisms. 



In the majority of the smaller bacteria which 

 have been examined, no distinction of peripheral 

 protoplasm and central body can be made out, and 

 Professor Biitschli believes that nearly the whole 

 organism corresponds to the " central part " of the 

 larger forms. 



These are some of the problems which have to 

 be attacked before we can satisfy our minds as to 

 the meaning which should be attached to the word 

 " cell." At the first glance we would imagine that 

 no word in science was clearer or better under- 

 stood ; but in the hands of the numerous enthusi- 

 astic workers in cytology its significance is ever 

 changing, as they steadily push forward towards a 

 more philosophical ideal. 



References. 

 (i) Max Verworn. — " Modern Physiology," 

 " Monist," April, 1894; ^.Iso " Nature," November 

 15th, 1894 (p. 58). 



(2) J. von Sachs. — " Physiolog Notizen," ii., 

 " Flora," 1892. 



(3) J. von Sachs. — " Physiolog Notizen," ix, 

 " Flora," Erganzungsband, 1895. 



(4) O. Biitschli. — " Ueber den Bau der Bacterien 

 u. verwandter Organismen," Leipzig, 1890. 



(5) O. Biitschli. — " Weitere Ausfiihrungen iiber 

 den Bau der Cyanophyceen, etc.," Leipzig, 1896. 



(6) E. Zacharias. — " Ueber die Zellen der 

 Cyanophyceen." " Botanische Zeitung," 1890. 



(7) E. Zacharias. — " Ueber das Verhalten d. 

 Zellkerns in Wachsenden Zellen." " Flora," 

 Erganzungsband, 1895. 



(8) F. Rosen. — " Beitr. z. Kenntniss d. Pflanzen- 

 zellen." " Cohn's Beitr. z. Biol. d. Pflanzen," 

 vii., 1895. 



Elmwood, Bickley, Kent; September, 1896. 



In the " Irish Naturalist " for November there is 

 an interesting article on " The Botany of a School 

 Playground in the heart of Dublin," by the Rev. 

 Thomas B. Gibson. Although the place seems an 

 unlikely one in which to find botanical specimens, 

 Mr. Gibson enumerates a number of plants he has 

 found in the playground of King's Hospital, 

 amongst others the somewhat uncommon green 

 hellebore, H. viridis. He says that the ground has 

 no unusual capabilities, nor has any attempt been 

 made to assist growth. He has, however, scattered 

 some few seeds himself on various occasions, but 

 most are self-planted. 



