March 17, 192 1] 



NATURE 



7S 



On the other hand, such colloids as gelatin have 

 not indicated any regular pattern when examined by 

 I X-rays. A fully developed network of oriented mole- 

 cules such as Dr. Sheppard describes should give 

 indications analogous to a crystalline structure when 

 thus examined. This X-ray method of investigation 

 is being applied in another department of the Uni- 

 versity of Bristol to the various forms of soap solu- 

 tions. It is hoped also to obtain fresh light on the 

 problem by the experiments now being carried out by 

 Miss Laing on the conduction of continuous current 

 through soap jellies. 



Dr. Sheppard 's demand that any "consistent" 

 \ theory of colloids should permit of the deduction of 

 ; all the physical properties from the chemical formula 

 alone, appears to over-estimate the extent to which 

 the manifold physical properties of gold and silver 

 sols of different degrees of subdivision and colour can 

 be deduced merely from the knowledge of the 

 chemical formulae of the metals. In conclusion, I 

 think his idea is at present too vague and not 

 sufficiently in accord with such facts as those men- 

 tioned to be likely to prove more fruitful than the one 

 it seeks to replace, incomplete as the latter is in the 

 absence of further experiment. 



James W. McBaix. 

 The Chemical Department, University of 

 Bristol, February 24. 



The Production of Living Glavellina Zooids in Winter 

 by Experiment. 



In a recent publication (" Sea-temperature, Breed- 

 ing, and Distribution in Marine Animals," Journ. 

 Mar. Biol. Assoc., vol. xii., No. 2, p. 351) the present 

 writer showed that there w^as every reason to believe 

 that the hibernation phenomena in many marine 

 animals are purely temperature effects. In* order to 

 test this view the positions of sixteen good colonies 

 of the beautiful Ascidian Clavellina lepadiformis 

 were marked on September i, 1920, on the wooden 

 piles of the West Wharf, Great Western Docks, 

 Millbay, Plymouth. This Ascidian usually appears 

 on these piles about the end of May and dies down 

 about the end of October, and has never been recorded 

 in winter. On Septemlier 15 and 30 the piles 

 were again visited and a record was made of those 

 colonies which had survived the marking. The posi- 

 tions of the colonies were found to be shown effec- 

 tively by three long wire nails driven into the piles 

 on the outside of the colonies at the apices of 

 imaginary triangles. On February 23 last the labora- 

 torv collector, Mr, Wm. Searle, who assisted in the 

 marking of the colonies, visited the piles at the West 

 Wharf and took careful scrapings between the nails 

 marking the positions where Clavellina colonies were 

 seen in September, .1920. 



The material obtained remained in the collecting 

 honey-jars on the floor of the laboratory until 8 p.m. 

 of Februarv 24. It was then examined, and anything 

 like a resting stage of an Ascidian was picked out, 

 cleaned a little, and transferred to clean water in a 

 glass dish. On February 25 at noon the material 

 was put into a warm room at a temperature of about 

 61° F., and distributed in a number of finger-bowls 

 in ordinarv tank-water passed through a Berkefeldt 

 filter. 



Little attention was given to the bowls beyond 

 changing the water on February 28, until March i, 

 when a distinct Clavellina zooid was found in one 

 dish and a bud in another. From that date onwards 

 the number of zooids and buds has increased, and at 

 the latest observation made, on March 8 there were 

 NO. 2681, VOL. 107] 



twelve living zooids or well-developed buds and two 

 well-developed zooids had been preserved. From the 

 beginning of the experiment to March i the tem- 

 perature did not fall below 60° F., and from an 

 inspection of the thermograph records the mean tem- 

 perature of the room is seen to be very nearly 61° F. ; 

 probably the mean temperature of the water in the 

 dishes would be slightly lower. Since March i the 

 mean temperature of the room and water has been 

 slightly higher. 



It is therefore highly probable that the awakening 

 of Clavellina from the resting stage is a pure tem- 

 perature effect. In this experiment tank- water was 

 deliberately used, and it is considered highly improb- 

 able that this water can be regarded as biologically 

 better than the water now surrounding the sleeping 

 stages of Clavellina in the sea. There remains, there- 

 fore, only the presence or absence of some recondite 

 chemical complex in the water as a possible factor 

 in aiding in the awakening of this Ascidian. The 

 existence of such a complex is, however, not 

 regarded as probable. 



Driesch has shown that Clavellina regenerates lost 

 parts with facility, and that starving or foul water 

 will also cause this Ascidian to absorb all its organs 

 and pass into an undifferentiated condition. It 

 would appear, however, that none of these factors 

 operate during the period of hibernation, since the 

 water at the West Wharf is undoubtedly more foul 

 during the period when Clavellina flourishes than 

 when it passes into and remains in the resting condi- 

 tion, and similar Ascidians in the same locality feed 

 and grow during the winter. Other forms which feed 

 in the same way, and probably on the same kinds of 

 food, as Clavellina also flourish and grow in the 

 same situation in winter. 



It would therefore seem that variations in tem- 

 perature are the normal stimuli for development and 

 differentiation in Clavellina, and the determination 

 of the actual point in temperature at which these 

 changes occur should afford a useful clue in attacking 

 the question of the underlying chemico-physical 

 changes. 



The winter resting stages of Clavellina are very 

 simple bodies; they are flattened expansions of trans- 

 parent gelatinous material (tunicin) with a mam- 

 millated surface containing a core of opaque yellow 

 tissue — apparently undifferentiated — which shows 

 mammillations corresponding to those in the gela- 

 tinous coat. In the development of the zooids the 

 mammillations swell and a core of tissue extends into 

 the swelling. The bud thus formed increases in size 

 and differentiates into the zooid. J. H. Orton. 



The Laboratory, The Hoe, Plymouth, 

 March 9. 



The Elementary Particle of Positive Electricity. 



Regarding the suggestions for the name of the 

 nvdrogen nucleus made by Prof. Soddy (Nature, 

 December 16, 1920, p. 502) and Dr. Prideaux 

 (Nature, December 30, 1920, p. 567), it w^ould seem 

 to be better to use the term "hydron" instead of 

 "hydrion," as being shorter and more euphonious. 



It may be recalled that the late Lord Kelvin used 

 himself, and tried in vain to induce others to use, 

 the term " electrion " instead of "electron." At this 

 late date it seems quite unnecessary to insist on the 

 retention of the extra svllable simply to have the word 

 "ion " retained in the longer term unless for the sake 

 of euphonv, as in "thermion." 



Andrew H. Patterson. 



University of North Carolina, February 19. 



