liECEEATm: SCIENCE. 



8^ 



Carefully executed studies of the arrange- 

 ment of tlie endochrome are still a desidera- 

 t\im, one which the late learned Professor 

 Smith hoped at some future day to supply, 

 and for which he had, previous to his death, col- 

 lected a goodly number of drawings. There 

 is no doubt it may sometimes assist towards 

 the ready distinction of species in the living 

 state, and its bright colours and elegant 

 arrangement would make a very handsome 

 series of illustrations ; we know of few 

 prettier than the common Cymatopleura solea 

 (Fig. 4). 



Fio. 4.— Cymatopleura solea, from tlie life, a, side 

 view ; 6, front view ; e, patches of endocbrome, 

 which,' on the front view, is seen to be mostly in 

 plates. 



A circulation of granules has been wit- 

 nessed in some of the Diatomacese. We 

 have ourselves seen it in the Surirella (Fig. 

 3), and two or three other fonns, and have 

 spent much time in attempts to ascertain if 

 it be not generally present. The exami- 

 nation is one requiring, however, such per- 

 fect management of all the details connected 

 with glasses, source of light, illumination, 

 and so on, with time at unlimited command, 

 that we obtained no satisfactory results, and 

 commend the investigation to such as are 

 possessed of all these requisites, with good 

 powers of observation, and no end of patience. 

 Eeady access to specimens in the full vigour 

 of life is also essential, and the ingenious 

 plan of growing them on damp sand in shal- 

 low saucers might be resorted to with success, 

 as an aid to the obtaining plenty of indivi- 

 duals in such condition, for purposes of study. 

 Doubtless, after all, a good deal wUl depend 

 on certain unknown conditions in the life of 

 the plant, as there are reasons for thinking 

 that it may be present at one of its stages. 



and absent at others, and favouring fortui- 

 tous circumstances may be required to render 

 all complete, and reward the happy inves- 

 tigator. In addition to the brief notice ot 

 this interestiug phenomenon .in the iiftro- 

 duotion to the " Synopsis of British Dia- 

 tomacese," vol. i., p. xxi., the translation from 

 the German of a paper by Professor Max- 

 Schultze, given in the " Quarterly Journal 

 of Microscopical Science" for October, 1858, 

 p. 13, should be consulted. Some of the 

 statements of this latter observer are cer- 

 tainly incorrect, and a friend who has had 

 peculiarly favourable opportxmities for study- 

 ing the forms mentioned, thinks others doubt- 

 ful ; but the subject is one of much interest, 

 well worthy of careful attention, and pro- 

 mises to add some useful facts to our very 

 scanty knowledge of the mysteries connected 

 with Life. 



The way in which Diatoms " increase and 

 multiply" has yet to be spoken of. The 

 general increase is by self- division, eachfrus- 

 tule dividing into two — a mode of growth at 

 first considered peculiar to, and which can 

 be studied with unusual advantage in the 

 tribe, but which is now known to be a very 

 general mode of increase in vegetable cells, 

 as also in the cells composing some of the 

 tissues of animals* Though we are not aware 

 that the division of the nucleus has actually 

 been seen by any observer, there can be no 

 doubt that such is the first stage of the pro- 

 cess ; the closeness with which it is sur- 

 rounded by granxJes of the endochrome 

 may, probably, account for this. Simul- 

 taneously with this, a rapid increase in the 

 quantity of endochrome takes place, by 

 which the two valves are pushed apart, and, 

 in order to protect the delicate internal 

 structures, a flinty band is formed, probably 

 by increase of a gelatinous investment of 

 each valve, with deposition of sUex. To this 

 protective covering of the newly-forming 

 structures, it is unfortunate that nearly every 

 observer has applied a different name. Pro- 



