May 29, 1885.] 



SCIENCE 



435 



thin, and transparent, so that the chief organs with- 

 in were visible through it. There were no eye-spots. 

 The mouth, when expanded, appeared as an ovoid* 

 sucker, with the orifice somewhat diamond-shaped; 

 and it was neither armed with teeth, nor provided 

 with a proboscis. The oesophagus is narrow, and 

 opens into a capacious stomach, which forms ten or 

 eleven horizontal discoid saccules, which were filled 

 with a blackish-brown liquid, apparently blood. The 

 stomach is surrounded by eight tortuous, 

 gland-like organs, which extend the entire 

 length of the body, and give rise to the 

 colored stripes seen through the skin. 

 These organs are composed of numerous 

 pyriform acini, and appear like racemose 

 glands, but their nature I did not deter- 

 mine. The specimens were preserved in 

 alchohol with the view of further investi- 

 gation, but they have softened to such a 

 degree that the examination has proved 

 unsatisfactory. From the conspicuous 

 gland-like organs and the habit of the 

 leech, I propose to name it Adenobdella 

 oricola. 



In the stomach of the same fish there 

 were some little tape-worms, which I sup- 

 pose to be the Taenia torulosa, originally 

 described from European species of Leu- 

 ciscus and other species of the same 

 family. The worms were white, filiform, 

 compressed cylindrical, and from three to 

 six inches long. The head is oval, with- 

 out rostrum or hooks, and with four equi- 

 distant, spherical, immersed bothria. The 

 neck is narrowed and moderately long. 

 The body widens to the posterior fourth, 

 and then gradually narrows. The segments are wider 

 than long, and not prominent. The generative aper- 

 tures are marginal, with the penes projecting; diame- 

 ter of the head, one-third of a line; greatest breadth 

 of the body, three-fourths of a line. 



Joseph Leidy. 



Mortality experience of life-insurance com- 

 panies. 



That figures have a great capacity for lying, and 

 that nothing needs closer watching than an argument 

 based on statistics, are facts which ought to be well 

 impressed on everybody's mind. On almost every 

 subject of public importance, — politics, finance, 

 economic policy, social science, — one is continually 

 solicited to believe in this or that doctrine because 

 statistics ' prove ' it to be true. And a large part of 

 the error that prevails on many of these subjects — 

 notably, on the question of free trade and protection 

 — is due, on the one hand, to the reckless way in 

 which statistics are handled by writers, and, on the 

 other, to the absence among their readers of a whole- 

 some suspicion of statistical arguments, and of the 

 abiding consciousness that statistics do not always 

 mean what they seem at first sight to say. 



Such being the case, it is a pity that Professor 

 Newcomb — than whom surely no one is more free 

 from the mental defects to which these errors are 

 usually due — should have made so many slips in a 

 recent article in Science on mortality statistics. One 

 cannot help asking whether Homer's nods come, like 

 misfortunes, many at a time. 



A curious logical slip occurs in the passage relat- 

 ing to the influence of occupation upon mortality. 

 " How little mere occupation has to do with viability, 

 is shown by the fact, that, while bankers and capital- 



ists suffer one-fourth less, brokers, speculators, and 

 operators suffer twelve per cent more, than the tabular 

 mortality." In other words, from the fact that in 

 two occupations seemingly very similar the rates of 

 mortality are widely different, the inference is drawn 

 that occupation has little or nothing to do with the 

 matter. Obviously, the true inference is, that either 

 the statistics are inadequate to the making of the 

 comparison in question, or that the occupations which 

 seemed to be similar are really widely different. If 

 we are sure the occupations are practically alike, we 

 must conclude that the statistics are insufficient, or 

 subject to a bias : if we are sure that the statistics are 

 sufficient and impartial, we must conclude that some 

 important difference is to be found in the occupations ; 

 and, in point of fact, there is a very striking difference 

 between the calling of an operator in stocks and that 

 of a legitimate banker or sound capitalist. 



In the same paragraph we are told that travelling- 

 agents have the greatest viability of all. This is 

 somewhat surprising ; but the fact is deprived of all 

 significance when one finds, on turning to the tables, 

 that the total number of deaths in this class was only 

 eight. So with regard to the excessive mortality of 

 the younger class. The whole number of deaths be- 

 tween the ages of seven and twenty is forty-seven, 

 as Professor Newcomb mentions, while the Ameri- 

 can table would make it thirty-three. An aggregate 

 excess of fourteen deaths is too slender a basis to rest 

 any inference upon, and is not so surprising as to 

 render an explanation absolutely necessary. It hap- 

 pens, however, that it is in a great measure explained 

 by the fact that (as pointed out in the text accom- 

 panying the tables) almost the entire excess occurs 

 among the lives insured under term-policies; i.e., 

 policies issued to extend over a particular period only, 

 and taken for the purpose of covering special risks. 



As to the most important point discussed by Pro- 

 fessor Newcomb, — whether Herbert Spencer, and 

 those who share his ' superstition,' are right in believ- 

 ing that the most active and enterprising Americans 

 injure their health, and shorten their lives, by too 

 great devotion to business, — I cannot think that these 

 mortality statistics are any thing like a 'sure test' 

 of the question. The class referred to is mixed up 

 with other classes; and, unless we can compare the 

 mortality in this class with the mortality in the same 

 class in England, our inferences must be very guarded 

 indeed. Moreover, there are many things affect- 

 ing selection — strictness of examination, privilege 

 of surrender, popularity of life insurance — which 

 may greatly differ in the two countries, and largely 

 influence the result. The great excess of mortal- 

 ity in the case of term-policies, and the considera- 

 ble deficiency in the case of paid-up policies, shown 

 by the Connecticut mutual tables, are instances of 

 this sort of phenomenon. And, even if we were in 

 possession of a perfectly fair comparison with Eng- 

 lishmen, it would still remain to consider whether 

 Americans would not, in the absence of habits com- 

 plained of, compare still more favorably with English- 

 men. On the question of the effect of overwork, and 

 worry, and ambition to become rich, a little bold 

 a priori reasoning is likely to lead to a sounder result 

 than can be derived from statistics not specially 

 designed to test the question. It may be remarked, 

 as throwing some light on the matter, that the actuary 

 of the Connecticut company, after observing that be- 

 tween the ages of fifty-six and seventy-five an undue 

 proportion of the deaths occur among those insured 

 for large amounts, adds, " These results suggest the 

 question whether those who insure for large amounts 

 — often, perhaps generally, men of good incomes, 



