13 



tions, will often be omitted. For instance, when the in- 

 fracellnlars and the monocellular organisms are exposed 

 to the temperature of liquid air, in water suspensions, or 

 in nutrient media, for an hour or so, it is certain that the 

 medium is hard frozen and hence this will not be stated 

 explicitly. 



The ordinary life stage and the usual culture conditions 

 are to be assumed if nothing to the contrary is mentioned. 

 For example, bacteria and yeasts are supposed to be in 

 the vegetative form and in aqueous media (solid or liquid), 

 if it is not specified that they have sporulated or that they 

 have been dried. 



The data to be reviewed w411 be arranged in sections 

 according to the type of organisms studied, the generally 

 accepted classification of plants and animals being fol- 

 lowed. Within a section, except if otherwise indicated, 

 the order is that of decreasing temperatures. There 

 results an unavoidable separation of related genera or 

 species. But, since the subject-matter is indicated in 

 italics, the reader will be able, without much effort, to re- 

 establish the natural correlations. Finally, then, each 

 separate paragraph usually contains an investigation on 

 a given subject, at a specified temperature and by a given 

 author or group of authors. 



The temperature shall always be given in degrees centi- 

 grade except if otherwise indicated. 



The terms "freeze" and "congeal" shall be used exclu- 

 sively when it is meant that the fluids of the material 

 under experimentation solidify. 



I. INFRACELLULARS 



By our inclusion of the infracellulars with living matter 

 we do not mean to imply anything as to their real nature. 



1. Vitamins and Hormones. The only information that 

 we found in the literature, on the action of low tempera- 

 tures on vitamins and hormones, was the observation that 



