28 



THE AMERICAN MONTHLY 



[February, 



1.506. Copaiba dissolves perfectly in 

 oil of cedar, and gives a liquid of the 

 index desired. Another liquid is also 

 obtained of an index of 1.5 10 and of 

 a dispersive power 0.0076, by dissolv- 

 ing with heat 7 parts of white vasel- 

 ine in 30 parts of copaiba. One 

 thus obtains a very thick liquid re- 

 maining where it is placed and not 

 acting upon asphalt nor shellac var- 

 nish in twenty-four hours' contact. If 

 this liquid is too thick it may be 

 thinned by adding a quantity of the 

 solution of copaiba in oil of cedar. 

 This liquid gives good images with 

 axial illumination, and shows per- 

 fectly the most minute details of dia- 

 toms with oblique light. 



The Phenomena of Growth 



among the Microscopic 



Forms of Life.* 



I do not come before you this even- 

 ing to discuss any of the problems 

 which lead us beyond the pale of di- 

 rect observation into the realms of 

 speculative thought. Although our 

 subject carries us to the dim border- 

 land of life — where it is not only im- 

 possible to distinguish plants from 

 animals, but where even the transition 

 from the inanimate to the living, the 

 inorganic to the organic, is imper- 

 ceptible, — yet I will not ask you to fol- 

 low me in any presumptuous efforts 

 to bridge, even in imagination, the nar- 

 row chasm which separates the one 

 from the other. It will suffice for our 

 purpose to know that the smallest 

 particle of matter that the microscope 

 can reveal, — and others even too 

 small to be defined by the best micro- 

 scopes known, smaller than the 

 length of an undulation of light, 

 may possess all the attributes of life. 

 We know that such particles live be- 

 cause they move and grow and multi- 

 ply. They possess, therefore, a cer- 

 tain organization which distinguishes 



* Address of the retiring President of the 

 New York Microscopical Society, delivered 

 at the Annual Reception, Fridaj' evening, 

 February 3d, 1882. 



them from non-living matter. How- 

 ever, the use of the word organization, 

 in this connection, has occasionally 

 given rise to misconceptions, for none 

 of the simplest forms of life are or- 

 ganized in the sense of having mus- 

 cles, nerves, vessels, or any differentia- 

 tion of parts for special functions. 

 Thus, we may find a simple spherical 

 mass of jelly, absolutely without a 

 trace of visible structure, manifesting 

 all the phenomena of life. Therefore, 

 organization, in this sense, does not 

 mean visible structure, but it relates 

 to the arrangement of the atoms and 

 molecules which compose the living 

 matter. 



A brief reference to the minute 

 animal known as the amoeba will 

 serve as an introduction to the sub- 

 ject before us. The amoeba consists 

 principally of a transparent, clear, or 

 granular mass of irregular shape, rang- 

 ing in size from -,^0" down to -g-oVo o^ ^^ 

 inch, or even smaller, resembling jelly, 

 which is known as bioplasm, or pro- 

 toplasiti — the physical basis of life. 

 Within the protoplasmic mass a more 

 dense, circular structure is sometimes 

 found, which is termed the nucleus, 

 the special function of which is still 

 a matter of investigation. The ex- 

 ternal layer of the protoplasm is some- 

 what more dense than the rest, but it 

 does not constitute a distinct mem- 

 brane or cell-wall, such as we find in 

 more highly developed organisms. 



If we conceive of the amoeba en- 

 closed within a membrane giving a 

 spherical shape to the organism, we 

 have the idea of a true cell, which 

 is regarded as the life-unit in both the 

 great kingdoms. It is by the assimila- 

 tive powers of cells that growth takes 

 place, and by their division all struc- 

 tural development proceeds. A typi- 

 cal cell consists of protoplasm and 

 nucleus within a membrane known as 

 the cell-wall. However, the life of 

 the cell resides in the bioplasm. It is 

 the semi-fluid contents and the 

 nucleus of the cell that lives 

 — all the rest is dead matter. It 

 seems absurd then, to regard the 



