64 MOISTURE AND PROTOPLASM [Ch. II 



must be beyond our ken. That these vital changes are some- 

 times exceedingly slight, is sufficiently indicated by the experi- 

 ments upon seeds performed by KocHS ('90), and referred to 

 on p. 60. That, however, slight changes are occurring even 

 in seeds is indicated by the fact that dessication-rigor cannot 

 continue indefinitely without loss of the power of revivifi- 

 cation. 



In the case of the rotifers, tardigrades, and nematodes, months, 

 and even years, may elapse without complete loss of capacity 

 for revivification. It is generally admitted, however, that in 

 cases of long-continued drought, the chances of revitalizing 

 upon moistening are much diminished.* In the case of seeds 

 it has been maintained that under certain conditions, such as 

 are realized in the mummy -graves of Egypt, life may persist 

 for more than a thousand years. However, the experiments of 

 MiJNTER ('47), and more especially of KocHS ('90, p. 683), 

 throw doubt upon this assertion, since they found that the 

 ancient, charred seeds fell to pieces in water like lime. As 

 for seeds preserved above ground in the ordinary way, KocHS 

 was assured by seedmen that they could not remain capable 

 of germination over 10 years. These facts go to show that 

 gradual changes occur in the dry protoplasm which are prob- 

 ably metabolic changes, i.e. vital changes ; and that therefore 

 life is hardly extinct in the very dryest protoplasm. 



The whole matter of desiccation-rigor is, after all, one with 

 which we are familiar in nature's larger laboratory. Many 

 Protista, when the ponds in which they live dry out, encyst 

 themselves and enter into a motionless condition in which they 

 resist the hot and dry summer winds. Thus, they may lie for 

 weeks, and, as experimentation has shown, they may be dried 

 for several years (see Butschli, '89, p. 1663, for references) 

 without loss of capacity for revivification. The same device 



* Thus Raim.tet ('92) says of Strongylus ruf escens : "I have seen them 

 regain their activity after 42 and even 68 days of desiccation. However, this 

 activity is much slower in manifesting itself. After the course of a month a 

 contact of 8 to 10 minutes is sufficient to bring them back to movement. . . . 

 After 68 days at least 50 minutes are required, and certain individuals have 

 shown activity only after 1 hour and 20 minutes. Moreover, the movements 

 were limited, and only a small number of cases contorted themselves like ordi- 

 nary AnguillulidEe." 



