THE BEGINNINGS OF LIFE. 319 



be seen to display the Brownian movement in a well- 

 marked degree. They seem to be reduced by the shortest 

 exposure to a temperature of 2i2F to the condition 

 of mere not-living particles, and then they become 

 subjected to the unimpaired influence of the physical 

 conditions which occasion these molecular movements 1 . 

 In many cases, however, organisms that are truly 



1 This statement concerning the two kinds of movements of Bacteria 

 and the power of boiling water to arrest only one of them, is almost word 

 for word what appeared in Nature' (No. 35, p. 171), for June, 1870. I 

 thought at the time that the statement was new in certain respects at 

 least I cannot refer to any similar statement in the writings of others 

 previous to that time. I was somewhat surprised, therefore, on 

 reading the quotation which is subjoined, to find that Prof. Huxley, on 

 Sept. 13, 1870, mentioned such distinctions as though they were quite 

 novel, and with the tacit suggestion that I was unaware of them. 

 Speaking of Bacteria, he says, ' They have two distinct kinds of move- 

 ments. The very smallest have merely a trembling movement ; those 

 which are elongated oscillate on a central point in their long axis rotating 

 whilst in an oblique position. This is one kind of movement. The 

 other kind of movement is a darting across the stage of the microscope, 

 sometimes in a straight line, sometimes accompanied by oscillations, 

 which gives a serpentine appearance to the moving Bacterium or chain 

 of Bacteria, whence the name Vibrio. These two kinds of movement 

 are not to be confounded. They must be explained as due to very 

 different causes ; and it seems to me that it is a confusion of these two 

 which is at the bottom of the mistakes made in the assertions as to the 

 survival of Bacteria, &c. after the application of very high temperatures.' 

 Prof. Huxley goes on to say that the temperature of boiling water and 

 other reagents which certainly destroy their life and abolish the last 

 kind of movement, does not put an end to the former ; and then adds 

 Do what you will, however, they retain their tumbling movement : 

 and this is a very misleading phenomenon.' (Quart. Jrnl. of Micros. 

 Science, October, 1870.) What follows is certainly a suggestion that I 

 had been misled by these phenomena, apparently because I was unaware 

 of the distinction then pointed out by Prof. Huxley. 



