HA RD WICKE'S SCIENCE- G OSSIP. 



275 



(4.) This is rather hypercritical. Mr. Pace 

 demurs to the use of the word "flammules," but 

 whether he thinks this has anything to do with the 

 validity of my theory I do not quite make out. 

 " Flame-like," which he proposes, has on his terms 

 the same objections as "flammules." The word is 

 adopted from Moquin-Tandon, and, moreover, is a 

 most legitimate term. If Mr. Pace will read the 

 various articles in the "Journal of Conchology," and 

 other scientific journals, he will find the word to be 

 in common usage.' 



(5-) I do not know so much about this (I refer to 

 Mr. Pace's statement). My specimens of the species 

 to which he refers do not show much, if any, 

 deviation from the nucleus-colours I have stated. 

 Two years ago, owning to the kindness of Mr. 

 Smith, I looked over several hundreds of specimens 

 (foreign and English) in the British Museum, and 

 could hardly find one exception to the fact as given 

 by me. Mr. Pace does not give us the colours of 

 the nuclei of the species he enumerates, and which 

 he has apparently in his collection. I wish Mr. 

 Pace had in this, and in others, stated his differences 

 more thoroughly. 



(6.) The highly- and variably-coloured Helices 

 would not be expected to as readily revert to the 

 horn-coloured as to the white variety. 



(7.) I know this simply as a matter of study. I 

 am not aware that it has ever been conceded that 

 any animal, as far as immediate progenitors are con- 

 cerned, has changed its marine habitat for a strictly 

 terrestial one. I do know, however, that it is con- 

 sidered that some animals primarily of terrestial 

 habit at have taken to one which is purely marine. 

 And, moreover, I know that it is thought by some 

 (Sollas and Milnes Marshall among others) that 

 freshwater faunas have had their origin from marine 

 aunas. Mr. Pace gives no reason as to why 

 Cyclostoma elegans has descended from marine 

 ancestors. The fact that species of Cyclostoma, 

 accompanied with distinctly freshwater species, have 

 been found in the lower series of the Bembridge 

 limestone, and in various Pleistocene deposits of fresh- 

 water origin negatives such a view. But the best 

 evidence is that this species has a gill in its early 

 stages which aborts as the embryo grows older 

 (compare Hatchett Jackson in Rolleston's "Forms 

 of Animal Life," 18S9 edition, pp. 479 and 482). 

 Again there is the fact that many freshwater species, 

 as the Succi?iea:, are amphibious, and that the change 

 from an aquatic to a purely terrestial life is indicated 

 in the interesting arrangement of mantle-cavity in the 

 amphibious Ampullaria as recorded by Jourdain and 

 Sabatier (Jourdain, C.R. 88, 1S79, Sabatier, ibid., 

 and A.N.H. (5) iv., 1879). 



(9.) May I ask Mr. Pace one question ? Are 

 points more complex than bands ? It seems to me 

 that he does not quite get the gist of Von Baer's law. 

 Are not bands and lines practically a confusion and 



coalescence of many points ? If points arise as a 

 resolution of bands then it seems to me it is a 

 retrogression from the complex to the simple, and 

 point blank to one of the most general laws of 

 nature. I do not think many readers will concede to 

 Mr. Pace this point of evidence against my theory. 



(10.) Mr. Pace says that what I have stated under 

 this heading illustrates my "misconception as to 

 what 'environmental conditions ' really are." I have 

 already replied to this under heading" (3). The 

 word " environment " I have always taken to mean 

 " surroundings." I do not know whether Mr. Pace 

 has an entirely different and private construction, or 

 meaning, to place on this common and oft-used word 

 of the English language. 



(11.) In some sense I do. Any field-naturalist will 

 support me when I say that the hyalinse are scarcely 

 ever found destroyed by birds as are their more con- 

 spicuous brethren, viz., H. aspersa, H. ?iemoralis, 

 II hortensis, and H. arbustorum. 



In conclusion, I hope I may not be considered 



hypercritical when I say that if Mr. Pace has — and he 



seems to have — a prejudice against, or doubts about 



the validity of the laws of Haeckel and Von Baer 



(believed in by all our best workers), on which my 



theory wholly rests, I cannot help it, and, therefore, 



my article was not written for him. I sent my 



article to Dr. Wallace and Dr. Romanes : the former 



writes me that he thinks my " view of the primitive 



colour is probably correct," and the latter also writes 



that to him " the theory it sets forth appears very 



probable." I am therefore prepared to adhere to it 



as a working hypothesis. 



J. W. Williams. 



NOTES ON SENNA. 



THIS well-known and important drug is the 

 produce of several species of the genus Cassia. 

 Senna leaves, as they are termed in trade, are the 

 leaflets of three or more different species, the leaves 

 themselves being of a pinnate form. 



They are of various shapes, and derived from 

 various sources. The East Indian or Tinnevelly senna, 

 which, by the way, is considered the finest kind, is 

 obtained from C. elongata, Lemaire. Characters — 

 leaflets lanceolate, rather downy beneath, with close- 

 pressed hairs. Largely cultivated in India, and 

 imported in large quantities from Tinnevelly. The 

 Tinnevelly senna, however, of retail shops, is gene- 

 rally a mixture of three species, hence not so good as 

 represented. 



The Alexandrian senna is the produce of two 

 species — C. acutijolia, Delile — characters : leaflets 

 ovate, with long spreading hairs near the under-side 

 of the mid-rib, and C. obovata, Colladon— character : 

 leaflets obovate, obtuse, slightly mucronate. These 

 two species are cultivated in Egypt and Nubia, and 

 imported in large quantities from Alexandria. 



