720 



SCIENCE 



[N. S. Vol. XXXH. No. 829 



Such latent life may be of two types, poten- 

 tial life and unmanif ested actual life. In the 

 first condition metabolism is completely sus- 

 pended as in the case of seeds kept at a very 

 low temperature. Its application in animal 

 life is not absolutely proved, and it is of 

 greater theoretical than practical importance. 

 Unmanifested actual life, however, was shown 

 to be possible by Loevenhoeck in the case of 

 Milnesium tardigradum, an animal organism 

 which renewed its life after a long period of 

 complete dryness. This form of latent life 

 has been used extensively by Carrel in his 

 work on transplantation of arteries and or- 

 gans. It is the condition which normally ex- 

 ists immediately after general death and con- 

 tinues until bacterial and enzymotic action 

 produces elemental death. Normally it lasts 

 but a few hours at the most, but may by strict 

 asepsis and a continued' temperature between 

 0° C. and 1° C. be maintained for weeks or 

 months. It is not a complete suppression of 

 metabolism, but is metabolism reduced to an 

 inappreciable minimum, to so low a grade that 

 the changes produced are not sufficiently de- 

 structive to prevent the revitalization of the 

 tissues. 



Until recently, these two types of latent life 

 were considered to be the only forms of life 

 which could be maintained outside of the ani- 

 mal body, after general death had occurred. 

 Stimulated, however, by the work of Harrison, 

 who a few years ago grew nerve cells of em- 

 bryo frogs in a drop of plasma, Carrel and 

 Burrows, of the Rockefeller Institute for Med- 

 ical Research, have recently carried out ex- 

 periments in producing actual manifest life in 

 adult mammalian tissue. Their brilliant re- 

 sults are reported in brief preliminary notes 

 in The Journal of the American Medical Asso- 

 ciation for October 15 and 29, 1910. The 

 principle of the experiments was extremely 

 simple ; the technique was rendered possible by 

 the careful organization of the department of 

 experimental surgery at the Rockefeller Insti- 

 tute. The experiments consisted in removing 

 bits of tissue from ma mm als immediately after 

 killing them, the most minute precaution be- 

 ing taken to procure asepsis, inoculating the 



tissue into a drop of plasmatic medium made 

 from the same animal, sealing it in a hanging 

 drop slide, placing it in a thermostat at 37° C, 

 and observing the changes in the tissue by 

 means of a microscope enclosed in a warm 

 chamber kept at the same temperature. 



The results of the experiments were uni- 

 form. In every case after from one to three 

 days, grovTth of the specimen was observed. 

 After a period of quiescence, varying accord- 

 ing to the nature of the tissue, granulations 

 made their appearance at the margin of the 

 tissue fragment, spindle and polygonal cells 

 were formed and rapidly grew out into the 

 surrounding lymph. The new tissue had 

 many characteristics of the parent material; 

 cartilage produced cartilage; spleen formed 

 cells closely resembling splenic pulp; and, 

 most striking of all, from the surface of bits 

 of kidney grew cell tubules, replicse of the 

 normal kidney tubes. Once started the 

 growth went on with wild rapidity, the cells 

 branching out in all directions, and the proc- 

 ess continuing for days until the nutritive 

 power of the plasmatic medium was exhausted, 

 and then, when once stopped by inanition, im- 

 mediately becoming reactivated upon reinocu- 

 lation into fresh plasma. Furthermore, frag- 

 ments of the newly formed tissue removed 

 from the parent mass and placed in fresh 

 media continued the same active prolific 

 growth as before its separation, the second 

 generation of cells closely resembling the first. 



The speed of growth of the tissues varied 

 according to the nature of the material; car- 

 tilage began to grow after three days and 

 progressed slowly; peritoneal endothelium and 

 arterial sheath were also slow in starting and 

 sluggish in progress; thyroid and spleen were 

 more active, showing changes in from thirty- 

 six to forty-eight hours; while in the case of 

 kidney, proliferation was seen after twelve 

 hours in the thermostat. Most interesting of 

 all, however, was the behavior of tumor tissue. 

 In their first article the authors report definite 

 growth of a bit of chicken sarcoma after nine 

 hours, and in the second publication a speci- 

 men of the same tumor had been seen actively 

 growing two and one half hours after inocula- 



