C. E. Beecher — Origin and Significance of Spines. 349 



peculiar skin disease known as ichthyosis sometimes produces 

 spiniform excrescences, and the victims are commonly called 

 " porcupine-men." The most celebrated instance was the 

 Lambert family. Haeckel 27 gives the following account of 

 this family : " Edward Lambert, born in 1707, was remarkable 

 for a most unusual and monstrous formation of the skin. His 

 whole body was covered with a horny substance, about an inch 

 thick, which rose in the form of numerous thorn-shaped and 

 scale-like processes, more than an inch long. This monstrous 

 formation of the outer skin, or epidermis, was transmitted by 

 Lambert to his sons and grandsons, but not to his granddaugh- 

 ters. The transmission in this instance remained in the male 

 line, as is often the case." Other similar examples are cited 

 by Gould and Pyle, 21 and the disease is described as " a morbid 

 development of the papillae and thickening of the epidermic 

 lamellae." 



Categories of Interpretation. 



Having thus far examined the factors governing the origin 

 of spines, and found that they could be grouped into a number 

 of distinct categories, it is now desirable to interpret these 

 results, and endeavor to arrive at the real significance of the 

 spinose condition. 



The two main generalizations which will be discussed are, 

 first, that spinosity represents the limit of morphological varia- 

 tion, and second, it indicates the decline or paracme of vitality. 



Spi?iositt/ a Limit to Variation. 



A number of data have 1 already been given, leading to the 

 belief that, on becoming spinose, organisms have reached a 

 limit of morphological variation. They may continue to develop 

 more and more differentiated and compound spines, but no new 

 types evolve out of such a stock. 



The subject may be treated in two ways, both leading to the 

 same conclusion. First, the stages and processes involved in 

 the growth of a spine itself may be studied, and next the 

 development of spines in the ontogenies and phylogenies of 

 animals and plants may be examined. 



The growth of a spine has already been described, and it was 

 shown that this type of growth may arise from specialization of 

 other ornamental features, such as nodes, ridges, and lamellae, 

 and also from the decadence of leaves, legs, etc. These obser- 

 vations and numberless others which could be made will be 

 sufficient to show that almost any kind of superficial structure, 

 as knobs, tubercles, ridges, laminae, reticulations, etc., has by 

 differential growth been changed into spines ; also, that organs 



Am. Jour. Sci. — Fourth Series, Yol. VI, No. 34. — October, 1898. 

 24 



