44 



HARDWICKE'S SCIENCE-GOSSIP. 



The Development of the Tadpole. — Having 

 seen Mr. C. Rousselet's note in the last number of 

 Science-Gossip, I am happy to be able to confirm 

 his observations on the existence of the ciliated 

 epidermal cells of the young tadpole. I have been 

 aware of the existence of the cilia in question for 

 three or four years, and had no idea that the fact was 

 unknown to biologists. I first noticed the currents 

 produced by the cilia while watching the circulation 

 of the blood with a |-in. objective. With this glass 

 the cilia are not easily seen, but the currents produced 

 by them are very distinct. In order to see the cilia 

 well, the tail should be gently scraped and the free 

 cells examined in a little water, with a |-in. objective ; 

 the cilia are then plainly visible. A very weak 

 solution of osmic acid brings them still better into 

 view, but quickly destroys the vitality of the cell ; 

 the cilia become stationary, and after a short time 

 seem to be attracted to the body of the cell and are 

 lost to view. I fear Mr. Rousselet will meet with no 

 success in his attempt to preserve stained sections, 

 owing to this capillarity between the cilia and the 

 cell, which comes into play as soon as the protoplasm 

 of the cell ceases to live. — P. E. IVallis, East 

 Grinstead. 



Our British Slugs. — Will the readers of my 

 communication with this heading in the January 

 number kindly make the few following emendations? 

 Line 28, "Beliz" should be "Bielz"; and "stabile," 

 " Stabile " on line 30. There is a very good figure of 

 Limax arborum, B. Ch., in Goteb. Handl. 1868, to 

 which reference can be made. It is interesting to note 

 that of Geomalcus there have been six new species 

 described by several French authors, Normand, 

 Baudon, Letourneaux, and Mabille, as G. inter- 

 medins, N. ; G. bourguignati, M. ; G. paladilhicuius, 

 M. ; G. moitessierianus, M. ; G. mabilli, B. ; G. ven- 

 dca7ius, L. ; all of which Heynemann in Malac. Bliitt. 

 xxi. has clearly shown to have been created from the 

 examination of young Arions. In this lies an evident 

 moral to all those who would name slugs, but from 

 an extensive and close acquaintanceship with slug- 

 lore and with slug- life. — J. IF. Williams, D.Sc. 



BOTANY. 



TOLYPELLA INTRICATA, IRREGULAR APPEARANCE 

 OF. — This rare species of the British Characere has 

 been remarkable, in that it " does not appear to 

 have been found for two successive years in any 

 locality," vide a review of British Characese, by 

 Messrs. Groves, p. 16. In the year 1883, when 

 botanising on a bleak day in March, and feeling 

 depressed with the barrenness of the day's search, this 

 plant was detected in a small pool between two woods 

 in S. Beds where it flourished luxuriantly during that 

 spring. The pool is only about nine feet long and 

 six feet wide, but the plant was developed in such 



perfection, that, in May, Mr. H. Groves came down 

 to gather some, in company with the writer. During 

 the ensuing summer the water all evaporated, and 

 the chara disappeared. During the following year, 

 18S4, when the pool was pretty well filled with water, 

 no trace of the plant could be detected, although it 

 was carefully examined at intervals of a few weeks,, 

 during the whole of the spring and summer. The 

 next year, 1885, it re-appeared in fair quantity, but 

 not so luxuriantly as in 1883, and it was left almost 

 untouched, so that its fruits might be matured. 

 Again, in the spring of 1886, the pool was carefully 

 examined, when the plant was found in small 

 quantities, this being, it is believed, the first instance 

 in which it has been detected in the same station for 

 two successive seasons, that is, in 1885 and 1886. 

 This irregularity of appearance seems equally well 

 marked in the Characese, as in some of the orchids. 

 As examples may be mentioned, Chara hispida, has 

 grown for several years in a pool at Totternhol, 

 whereas, at Simbury, it has only grown in one season ; 

 Chara vulgaris almost filled a pond at Brummugham 

 one season, and was entirely absent the next ; Nitella 

 mucronata, abundant in a pool near Bedford in 1882, 

 but has not re-appeared there, although it has been 

 detected in the adjoining river. Nitella opaca, in one 

 pool at Snodan ; it grew in 1882, but has been absent 

 since, whereas, at another station about a mile distant, 

 the same species has appeared several years in suc- 

 cession. The year 1886 was remarkable for the 

 scarcity of Characeaa in this district, which have been 

 less abundant . than in any year since 1S82. The 

 foregoing remarks are given in the hope, that they 

 may stimulate observation on the hitherto unex- 

 plained causes of the irregularity in appearance of 

 some of our native plants, a true solution of which 

 would probably only be obtained by a series of data 

 extending over a succession of years. — J. Saunders, 

 Luton. 



Amphipleura pellucida.— On p. 258, Mr. W. E. 

 Simmonds asks how this diatom is to be resolved 

 by Seibert's j'gth water immersion, and confesses to 

 having wasted many hours in attempting to see the 

 stria? ; now Siebert's glass having, or professing to 

 have, a numerical aperture of a little over 0*99, it 

 would be possible theoretically to resolve stria; of 

 104'OwO to the inch with the aid of monochromatic 

 light, the ordinary amphipleura has striae about as 

 fine as 93 - ooo to 96 - ooo to the inch. I do not think 

 the margin is sufficient, as in practice these cheap 

 glasses never work up to theory. If Mr. Simmonds 

 is anxious to see amphipleura, I would advise him 

 either to get an easy frustule of the Peruvian variety, 

 with stria? about 6o - ooo to the inch, or to possess 

 himself of a Homogeneous oil immersion objective. 

 He will then be able to gratify himself with a sight of 

 the " bars " on amphipleura. — P. E. JVallis, East 

 Grinstead. 



