230 NATURAL SCIENCE. April, 



destroyed slowly. The amoeboid cells apparently were unable to 

 retain hold on a nematode when that was wriggling actively, but as 

 soon as it became quiescent the cells laid hold of it. 



The dorsal pores are not simple apertures, but are crossed by 

 strands of muscle which act as sphincters. It was found that the 

 application of an irritant to any part of the skin at once resulted in 

 the discharge of quantities of the coelomic fluid, containing numerous 

 amoeboid ceils. When exposed to too dry, hot, or cold a tempera- 

 ture, the earthworm, until its nervous system became paralysed, 

 discharged quantities of the fluid. As Professor Baldwin Spencer 

 has already suggested. Dr. Lim Boon Keng admits that simple lubri- 

 cation may be part of the function of this discharge. But from the 

 abundance and activity of the phagocytic cells in it, he thinks that 

 its chief function is to prevent the intrusion of the microbes which 

 must be abundant in the soil and humus inhabited by earthworms. 



Microbes and Butter. 



In his excellent handbook on the chemistry and bacteriology 

 of the dairy (" Milk : Its Nature and Composition." London : 

 A. & C. Black, 1895. Price 3s. 6d.) Dr. Aikman makes a just 

 and suggestive comparison between the work Pasteur did for the 

 brewing industry and the bacteriological work that is required in 

 butter-making and other dairy-work. Notwithstanding the efforts of 

 county councils and the dissemination of various excellent handbooks 

 like this by Dr. Aikman, it seems difficult to impress on the British 

 farmer the necessity and the commercial advantage of a knowledge 

 of microbes. Before Pasteur worked at the yeasts of beer and wines, 

 the same uncertainty reigned in breweries that now rules the dairy. 

 Wort treated in apparently the same way, and made from identical 

 qualities of material, sometimes would produce an agreeable beer, 

 sometimes a ropy or stringy or sour decoction. Pasteur isolated the 

 microbes that caused the different kinds of fermentation, and showed 

 how to prepare pure cultures of the proper organisms, and brewing 

 and wine-making suddenly developed into a certain and profitable 

 industry. At the present time, when butter is to be made, the cream 

 is soured or ripened. Sometimes the proper agreeable flavour appears, 

 sometimes the cream becomes tasteless or rancid or otherwise un- 

 pleasant. The different processes that occur during the period of 

 ripening are the work of different kinds of bacteria. Already one or 

 two of them have been isolated, and it seems likely that pure cultures 

 of butter-flavouring bacteria may soon come to be supplied, just as 

 Pasteur produced the proper kinds of pure yeasts. 



DiABROTICA IN NoRTH AMERICA. 



In the Journal of the New York Entomological Society (November, 

 1895), Mr. F. M. Webster has an article about some forms of this 



