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SCIENTIFIC SIDE-LIGHTS 



imperfection 

 mprint 



Pulp. We saw here, for the first time, the 

 splendid hyacinthine macaw (Macrocercus 

 hyacinthinus, Lath., the araruna of the 

 natives ) , one of the finest and rarest species 

 of the parrot family. It only occurs in the 

 interior of Brazil, from 16 S. lat. to the 

 southern border of the Amazons Valley. It 

 is three feet long from the beak to the tip 

 of the tail, and is entirely of a soft hya- 

 cinthine blue color, except round the eyes, 

 where the skin is naked and white. It flies 

 in pairs, and feeds on the hard nuts of sev- 

 eral palms, but especially of the " mucuja " 

 (Acrocomia lasiospatha). These nuts, which 

 are so hard as to be difficult to break with a 

 heavy hammer, are crushed to a pulp by the 

 powerful beak of this macaw. BATES Nat- 

 uralist on the River Amazon, ch. 4, p. 649. 

 (Hum., 1880.) 



1597. IMPOSTURE PRACTISED BY 

 COWBIRD We often see these birds feed- 

 ing near cattle in the pastures, always in 

 small flocks, for they do not pair nor even 

 construct a nest, the female laying her egg 

 in the nest of another and generally smaller 

 species. Few birds seem aware of the im- 

 posture, and not only do they incubate the 

 egg, but they may attend to the demands of 

 the young eowbird at the expense of their 

 own offspring, who sometimes die of star- 

 vation. Even after leaving the nest the 

 young parasite continues its call for food, 

 and when seeing a Maryland yellowthroat 

 or some other small bird feeding a clumsy 

 fledgling twice its size, one wonders it does 

 not detect the deception. CHAPMAN Bird- 

 Life, ch, 7, p. 174. (A., 1900.) 



1598. IMPRESSION ON PREPARED 

 NERVE-CENTER Apperception The Lov- 

 ers Tap The Friend's Voice. This reen- 

 forcement of ideas and impressions by the 

 preexisting contents of the mind was what 

 Herbart had in mind when he gave the name 

 of " apperceptive attention " to the variety 

 we describe. We easily see now why the lov- 

 er's tap should be heard it finds a nerve- 

 center half ready in advance to explode. 

 We see how we can attend to a companion's 

 voice in the midst of noises which pass un- 

 noticed tho objectively much louder than the 

 words we hear. Each word is doubly awa- 

 kened ; once from without by the lips of the 

 talker, but already before that from within 

 by the premonitory processes irradiating 

 from the previous words, and by the dim 

 arousal of all processes that are connected 

 with the " topic " of the talk. The irrele- 

 vant noises, on the other hand, are awa- 

 kened only once. They form an unconnected 

 train. The boys at school, inattentive to 

 the teacher except when he begins an anec- 

 dote, and then all pricking up their ears, 

 are as easily explained. The words of the 

 anecdote shoot into association with exci- 

 ting objects which react and fix them; the 

 other words do not. JAMES Psychology, vol. 

 i, ch. 11, p. 450. (H. H. & Co., 1899.) 



1599. IMPRESSION, WEAK, OBLIT- 

 ERATED BY STRONG Tick of Clock 

 Light of Stars Slight Weight Added to 

 Heavier Weight. Every one knows that in 

 the stillness of night we hear things which 

 are unperceived in the noise of day. The 

 gentle ticking of the clock, the distant 

 bustle of the streets, the creaking of the 

 chairs in the room, impress themselves upon 

 our ear. And every one knows that amid 

 the confused hubbub of -the market-place 

 or the roar of a railway-train we may lose 

 what our neighbor is saying to us, or even 

 fail to hear our own voice. . . . The 

 tick of the clock is a weak stimulus for our 

 auditory nerves, which we hear plainly when 

 it is given by itself, but not when it is added 

 to a strong stimulus of rattling wheels and 

 all the other turmoil. The light of the 

 stars is a stimulus for the eye; but if its 

 stimulation is added to the strong stimulus 

 of daylight, we do not notice it, altho we 

 sense it clearly when it is joined to the 

 weak stimulus of twilight. The gram 

 weight is a stimulus for our skin which we 

 sense when it is united to a present stimulus 

 of equal strength, but which vanishes when 

 it is combined with a stimulus of a thou- 

 sand times its own intensity. WUNDT Psy- 

 chology, lect. 2, p. 22. (Son. & Co., 1896.) 



1600. IMPRESSIONS OF CHILD- 

 HOOD A STIMULUS TO SCIENTIFIC 

 PURSUITS Stories of Adventure Combine 

 with Love of Science. The longing wish I 

 felt to behold the Pacific from the lofty 

 ridges of the Andes was mingled with recol- 

 lections of the interest with which, as a boy, 

 I had dwelt on the narrative of the ad- 

 venturous expedition of Vasco Nunez de 

 Balboa. That happy man, whose track Pi- 

 zarro followed, was the first to behold, from 

 the heights of Quarequa, on the Isthmus of 

 Panama, the eastern part of the great 

 " South Sea." The reedy shores of the Cas- 

 pian, viewed from the point whence I first 

 beheld them, viz., from the delta formed 

 by the mouths of the Volga, cannot certainly 

 be called picturesque, yet the delight I felt 

 on first beholding them was enhanced by the 

 recollection that, in my very earliest child- 

 hood, I had been taught to observe, on the 

 map, the form of the Asiatic inland sea. 

 The impressions aroused within us in early 

 childhood, or excited by the accidental cir- 

 cumstances of life, frequently, in after- 

 years, take a graver direction, and become 

 stimulants to scientific labors and great en- 

 terprises. HUMBOLDT Views of Nature, p. 

 417. (Bell, 1896.) 



1601. IMPRINT OF RAIN-DROPS 

 Enduring Record of the Evanescent. 

 When a shower of rain falls, the highest 

 portion of the mud-covered flat is usually 

 too hard to receive any impressions ; while 

 that recently uncovered by the tide near the 

 water's edge is too soft. Between these 

 areas a zone occurs, almost as smooth and 

 even as a looking-glass, on which every 

 drop forms a cavity of circular or oval form, 



