1886.] 



MICEOSCOPICAL JOUENAL. 



173 



Zeiss, of gradually increasing numeri- 

 cal apei'tui'e, until, during the last year. 

 Dr. Dallinger received a |^, a ^^ , and a 

 giji^, each having a numerical aperture 

 of 1.5, made by Mr. Powell. With 

 these fine lenses much has been dis- 

 covered that has hitherto been hidden. 



The most important results are the 

 elucidation of the process of develop- 

 ment and growth of the nucleus in the 

 organisms studied. These are so low 

 in the scale of existence that they can- 

 not be classed as either animal or vege- 

 tal, and may be assumed to represent 

 the nucleus in a very elementary con- 

 dition. Previous researches had al- 

 ready shown that after repeated fission 

 of the monads, always characterized 

 by division of the nucleus, two individ- 

 uals coalesce, and become quite still un- 

 til the investing sac bursts and sets free 

 a cloud of innumerable germs, so mi- 

 nute as to be almost invisible. These 

 were observed to grow up to a certain 

 size, when the growth was tempora- 

 rily arrested. By the use of the finest 

 lenses the arrest of growth has been ex- 

 plained. It is the nucleus that grows 

 from the minute germs, and the arrest 

 of growth is due to internal changes 

 which result in the development of the 

 nuclear structure. Up to this point no 

 internal structure is to be seen ; but a 

 granular structure can then be ob- 

 served to develop, when the full aper- 

 ture of the new lenses is employed, and 

 after this condition is fully attained, the 

 growth of the body substance around 

 the nucleus begins. One other impor- 

 tant observation was made at the same 

 time, w^hen the development of the 

 flagella from the nucleus itself was 

 distinctly followed. 



It has also been discovered by the 

 aid of the new lenses, that fission be- 

 gins in the nucleus, and not in the 

 body substance as hitherto observed. 

 We will not attempt a description of 

 the appearances presented by the nu- 

 cleus previous to division, but they are 

 remarkal)le, and show the importance 

 of critical examination in this field. 



In the case of coalescence of two 

 nucleated monads the changes of the 



nviclei have been follow^ed, and the 

 results seem destined to throw much 

 light upon the phenomena of conjuga- 

 tion among simple organisms. The 

 nuclei fuse together, but finally the 

 nuclear contents seem to become dif- 

 fused throughout the sarcode body 

 and lost. Then the organism gives 

 rise to the germs of a new generation. 



This brief and inadequate notice 

 affords but a faint idea of the great 

 and painstaking work of Dr. Dallin- 

 ger, wdiich is surely leading to a 

 knowledge of the operations of life, 

 deeper and clearer than would be 

 possible without the optical means 

 at his disposal. We cannot but think, 

 in this connection, of the work upon 

 the growth and functions of nuclei 

 so long in progress in Germany, and 

 it seems not improbable that Dr. 

 Dallinger has advanced further in 

 some respects than any other investi- 

 gator, because he has been so anxious 

 to avail himself of optical appliances 

 superior to any hitherto used. It 

 is also noticeable, and this may be a 

 very significant fact, that although 

 he speaks of a plexus-like structure, 

 he does not figvnx or describe any 

 network structure in nucleus or sar- 

 code such as we are tavight to believe 

 characterizes living matter. The 

 gmnules of the nucleus are not de- 

 scribed as connected by threads, the 

 sarcode is structureless. We have 

 often thought the network structure 

 might be due to imperfections in the 

 optical apparatus, or to a delusion 

 of imperfect vision. Surelv Dr. 

 Dallinger would not overlook, with 

 his fine lenses, a structure easily seen 

 with inferior ones. 



No one can read Dr. Dallinger's 

 contributions without a feeling of 

 respect and admiration for those 

 qualities of mind and industry that 

 have enabled him to carry on such 

 difficult observations so long and 

 successfully. H. 



Jottings by the Way. — It is the 



29th of July, and high time that our 

 wandering thoughts should be direc- 



