FISHERY BVLLETIM: VOL. 69. NO, 3 



body of literature has accumulated, with conspic- 

 uous bulges in the early years (1884-1930) and 

 in the past decade (1960-70), but with a very 

 narrow waist during the period 1930-60. 



Studies of humoral defenses of the larger 

 Crustacea during the past 5 years (1965-70) are 

 curiously reminiscent of work reported by Can- 

 tacuzene and his associates during the period 

 1912 to 1934, with the very important difference 

 that most of the modern work includes elements 

 that were largely missing from earlier reports, 

 such as details of procedures, sujiporting data, 

 adequate controls, and attempts at quantitation 

 of results. 



Because so much of the literature produced be- 

 fore 1940 lacks adequate quantitation and fails 

 to jn'ovide details of techniques used, it is often 

 difficult to relate results to those of more recent 

 studies. Bang (1967b) has deliberately ad- 

 dressed himself to a rejietition of earlier studies 

 but has used modern methods in an attempt to 

 improve the relationship. Other recent reports, 

 even though based on species other than those 

 used in earlier studies, constitute ree.xaminations 

 of the concepts and general findings of the early 

 investigators. 



It is difficult to determine why the early work 

 on immune responses in invertebrates so effec- 

 tively begun by JMetchnikoff, Cantacuzene, Cue- 

 not, Bruntz, and others during the late 19th 

 century and the early 20th century seemed to 

 lose impetus and then virtually cease until re- 

 cently. It is apparent from the literature, 

 though, that research on invertebrate defenses, 

 initiated so auspiciously, receded for a number 

 of decades to the backwaters and eddies of the 

 mainstream of advances in immunology, which 

 was concentrated on the homoiothermic vei-te- 

 brates. This may be explained in part by a 

 natural and necessary concentration of research 

 interest on human and mammalian immune re- 

 sponses (most immunologists wei'e — and still 

 are — generally associated with medical schools 

 and hospitals) . Part of the explanation also may 

 be that earlier work failed to disclose any defense 

 mechanisms in invertebrates that seemed funda- 

 mentally or conceptually different from those 

 that were being elucidated for the vertebrates. 

 More importantly, the explanation may have 



been that much of the earlier work failed to 

 indicate any immunologic responsiveness in the 

 invertebrates tested. In spite of occasional suc- 

 cesses, the "inability of invertebrates to respond 

 to the introduction of antigen by formation of 

 antibodies" became a sort of dogma among many 

 of the early biologists, as was pointed out by 

 Cantacuzene (1923b). Failures to find responses 

 may have been due jiartly to choice of inocu- 

 lum with negligible antigenicity in the experi- 

 mental invertebrate. Two factors may have 

 caused the recent resurgence of interest among 

 biologists in comparative immunology (which 

 is gradually beginning to include the lower 

 vertebrates and the invertebrates): (1) an 

 evident need to reexamine the conceptual and 

 evolutionary basis of immune responses and (2) 

 an interest in understanding the internal de- 

 fenses of invertebrates, which allow them to 

 survive in a microbe-rich environment even 

 though they lack the specific antil)ody response 

 characteristic of most vertebrates. 



The subject matter of the present review is 

 one that has been treated previously (Cantacu- 

 zene, 1923b: Huff, 1940; Baer, 1944; Bang 

 1967b; Levin, 1967; Tripp, 1969; Rabin, 1970b; 

 Bang, 1970). Many of those iiapers, however, 

 were broad considerations of the invertebrates 

 as a whole, and discussions of internal defenses 

 of Crustacea were often more or less incidental. 

 It is interesting — as Good and Papermaster 

 (1964) pointed out — that no review of inverte- 

 brate immunity has em])hasized induced re- 

 sponses. A recent, and excellent, 2-volume text 

 on the physiology of Crustacea (Waterman, 

 1960) does not include a detailed consideration 

 of the very imjiortant subject of internal de- 

 fenses, except for reference to hemocytes and 

 phagocytosis (Maynard, 1960; Parry, 1960), 

 and a consideration of hemolymph coagulation 

 (Florkin, 1960). 



The general plan for this review is to discuss 

 some of the early literature, after a brief pre- 

 liminary statement about concepts and termi- 

 nology, and a summary of known diseases of 

 Crustacea. More recent studies will then be 

 considered by categories of cellular and humoral 

 systems: phagocytic, bactericidal, lytic, agglu- 

 tinating, iJrecii'jitating. phage clearing, and anti- 



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