302 



NATURE 



{Aug. 15, 1872 



observers, and has convinced them that these organisms 

 have not arisen from accidentally introduced spores, but 

 by a true heterogenetic transformation of the substance 

 examined. Ur. Lionel Bcale has discovered lowly vege- 

 table organisms " in the interior of the cells of animals, 

 and in the very centre of cells with walls so thick and 

 strong that it seems almost impossible that such soft bodies 

 could have made their way through the surrounding 

 medium." Many other observers have even watched the 

 transformation of the contents of healthy epithelial cells 

 into Bacteria and Vibriones ; and well-developed Fungi 

 have been found within the uninjured eggs of birds and 

 serpents. Now, all these facts, and a vast number of 

 others detailed by Dr. Bastian, are claimed to be in com- 

 plete harmony with the|facts he has already established by 

 his experiments with hermetically closed flasks, and with 

 the theory of Archebiosis, while they have always offered 

 immense difticulties to the advocates of Homogenesis, 

 and have never been explained but by means of pure 

 assumptions of a most improbable character. 



W'e next come to the consideration of true Hetero- 

 genesis among lower organisms. Ur. Braxton Hicks has 

 observed the production of Amccbic by the transformation 

 of the chlorophyll and protoplasmic contents of the cells 

 of Moss radicles. Mr. H. J. Carter has closely followed 

 the changes occurring in the cells of Nitella, one of the 

 Characea;, resulting in the formation of Monads and 

 AmcebK, as represented in Fig. i. A vast number of 

 observations of a similar character by many different ob- 

 servers are detailed, showing that the chlorophyll vesicles 

 of Alga; are sometimes metamorphosed even into Pedias 

 treic, Desmids, and Diatoms. 



But we must pass on to still more remarkable facts. 

 The cell contents of Conferv;e give rise to Euglen^e 

 and Astasia;, beautiful green organisms which abound 

 in stagnant water, and these undergo transforma- 

 tions into a variety of higher or lower organisms, 

 such as Diatoms, Amoebae, and Ciliated Infusoria, 

 the latter process being represented in Fig. 2. But 

 Ciliated Infusoria themselves undergo transformation 

 into various forms of lower animals, among others into 

 Rotifers. The low Euglena; are also transformed into 

 cither Rotifers, Tardigrades, or Nematoids, and the latter 

 even grew into well-developed males and females (Fig. 

 3). Still more extraordinary, if possible, is the trans- 

 formation of the minute Algoid Chlorococcus into the 

 large, complex, and well-known Rotifer, Hydatina sciila. 

 Concerning the reality of these transformations, astound- 

 ing as they are. Dr. Bastian assures us he entertains not 

 the slightest doubt, having traced them through all their 

 stages. The extreme prevalence and almost universal 

 distribution of certain common forms of Rotifers, Tardi- 

 grades, and Nematoids, whose germs or ova are unusually 

 large, and have been proved not to be universally pre- 

 sent in the atmosphere, is inexplicable to those who 

 disbelieve in the occurrence of heterogenetic transforma- 

 tion. Not only is it said to be proved that such trans- 

 formations occur among Alg;e, Fungi, Lichens, and 

 Mosses, in every group of animals belonging to the class 

 Scolecida, and in some of the lowest Annelida, but also 

 in some of the lowest Arthropoda. In concluding this 

 part of his subject, our author remarks : — " The fact that 

 animals with such distinct and specific organs should arise 

 in this definite manner from the reproductive products of 

 a plant, will doubtless seem to many to flavour more of 

 fable than of fact. After the observations which have 

 been detailed, however, we must accept the occurrence of 

 such phenomena as established facts, just as we are com- 

 pelled, and are now quite accustomed, unhesitatingly to 

 believe in the reality of other eciually inexplicable phe- 

 nomena. When we are able really to explain the reason 

 of the processes by which one minute vesicular mass of 

 fatty and albuminoid particles develops into a man, 

 another into a fish, and another into an insect, we may 



then, with a little more show of reason, think of rejecting 

 other more or less similar facts because they are incom- 

 prehensible." 



Passing now from facts and observations of which we 

 have only been able to indicate the character and extent 

 by a few examples, Dr. Bastian proceeds to discuss the 

 nature of "individuals" and "species" by the aid of the 

 new light these researches have thrown upon them. He 

 adopts the definition of an " individual " given by Herbert 

 Spencer as being any organised mass " having a structure 

 which enables it continually to adjust its internal relations 

 to e.xternal relations, so as to maintain the equilibrium of 

 its functions," and would define species to be any assem- 

 blage of individuals which are enabled for many genera- 

 tions to reproduce their like. But between these two he 

 believes we must now establish a third category, for which 

 he proposes the term " Ephemeromorphs," to include all 

 those various forms which, although they sometimes pro- 

 duce their like, are shown to be interchangeable, and 

 which, occasionally or regularly, arise from, or give birth 

 to, forms quite distinct from themselves. All groups in 

 which there is no differentiation of sexes are probably 

 Ephemeromorphs, and the phenomenon of "alternate 

 generations " in sexual animals is thought to be a recur- 

 rence to a partially Heterogenetic mode of reproduc- 

 tion. 



The facts of Heterogenesis, if established, will un- 

 doubtedly largely modify our views as to the universality 

 of the action of " Natural Selection." They seem to show 

 that among the lower organisms, unknown laws of 

 " polarity " akin to those which influence the production 

 of crystals, but of infinitely greater complexity, directly 

 cause the development of a vast variety of forms ; while 

 conditions of existence to a great extent determine the 

 special forms that shall arise in each individual case. 

 For such creatures " laws of heredity " hardly exist, and 

 if so, Natural Selection can have little or no power. If 

 we consider the enormous variety of forms that have been 

 here shown to arise by Heterogenesis, it becomes evident 

 that the field of action for Natural Selection becomes 

 thereby considerably reduced. Again, the experiments 

 detailed by Dr. Bastian prove the overwhelming im- 

 portance of external conditions in determining the form 

 that shall be assumed by many of the lower organisms, 

 just the reverse of what has been found to obtain among 

 the higher animals. And, what is still more important, the 

 varying conditions do not act by producing changes in the 

 adult organism which may be transmitted to their off- 

 spring, but actually so modify the developing germs as 

 from a similar starting point to produce organisms which 

 would rank as of distinct species, genera, or even families. 

 The change produced seems to be quite incommensurate 

 with the modified conditions which lead to it, and we are 

 thus forced to accept some form of belief in innate ten- 

 dencies or laws of progressive development, dependent on 

 the polarities, forms of equilibrium, and attractive or re- 

 pulsive properties of the complex physiological units of 

 which organisms are built up. Such views are generally 

 repudiated by modern thinkers ; but Dr. Bastian believes 

 they arc necessitated by the facts now brought forward, 

 and that they are really not only in harmony with, but 

 .almost necessary deductions from, the principles of the 

 philosophy of evolution. 



The phenomena of Heterogenesis also lead us to con- 

 clusions as to the rate of change in time of lower organ- 

 isms exactly the reverse of those generally held. From 

 having mainly studied the higher forms of life, and from 

 having ascertained that the complex actions and reactions 

 of such organisms on each other have been more efficient 

 in producing specific changes than mere variability or the 

 influence of changed conditions, Mr. Darwin has been led 

 to the conclusion that the rate of change of the early 

 forms of life, which had far less complex actions and reac- 

 tions among themselves, must have been exceedingly slow. 



